fix(cctv): make the Houston TranStar pack opt-in

TranStar's disclaimer prohibits copying, distribution and external framing
of specific images without TxDOT's prior written permission, so the pack
no longer loads by default. It now uses envOptIn and loads only when
CCTV_HOUSTON_ENABLED=1, the same pattern as NYC DOT and Via Lietuva.

- DATA_SOURCES.md: replace the licence column with the disclaimer's terms
  and a link, and document the opt-in
- Ambient stills for Houston refresh every 3 minutes, matching TranStar's
  stated snapshot cadence
- README, CHANGELOG, CURRENT-STATE and .env.example describe the pack as
  opt-in; the README camera count no longer includes Houston
- Tests cover the default-off and =0 cases and the opted-in catalog path

DATA_SOURCES.md

@@ -65,7 +65,7 @@ How to read this:
 | **Statens vegvesen** (catalog `ogckart-sn1.atlas.vegvesen.no`, frames `kamera.atlas.vegvesen.no`, HLS `kamera.vegvesen.no`) | CCTV camera catalog + frames + live HLS video, Norway road cameras                                                                                   | [NLOD 2.0](https://data.norge.no/nlod/en/2.0) — attribution REQUIRED | "Contains data under the Norwegian licence for Open Government data (NLOD) distributed by Statens vegvesen" |
 | **NYC DOT Traffic Management Center** (`webcams.nyctmc.org`) | CCTV camera catalog + frames, New York City five boroughs | NYC DOT requires developers to sign a [data-sharing agreement](https://www.nyc.gov/html/dot/html/about/datafeeds.shtml) for the camera feed. **Off by default**; enable only under your own agreement | "NYC DOT Traffic Management Center" + NYC DOT's required application disclaimer (in the Data attribution popover) |
 | **City of Toronto Open Data** (`opendata.toronto.ca`)                 | CCTV camera catalog + frames, Toronto city streets                                                                                  | [Open Government Licence – Toronto](https://www.toronto.ca/city-government/data-research-maps/open-data/open-data-licence/) — attribution REQUIRED                                                                                                                                                                                                    | "Contains information licensed under the Open Government Licence – Toronto"                                                                 |
-| **Houston TranStar** (`traffic.houstontranstar.org`, frames `www.houstontranstar.org`) | CCTV camera catalog + frames, Greater Houston | Public Houston TranStar traffic camera stills | "Houston TranStar" (courtesy) |
+| **Houston TranStar** (`traffic.houstontranstar.org`, frames `www.houstontranstar.org`) | CCTV camera catalog + frames, Greater Houston | No licence. The [TranStar disclaimer](https://traffic.houstontranstar.org/disclaimer.aspx) (Content Usage) prohibits copying or distribution, and external framing or linking to specific images, without TxDOT's prior written permission. Off unless `CCTV_HOUSTON_ENABLED=1` | "Houston TranStar" (courtesy) |
 | **GBFS (Lyft / BCycle / Social Bicycles / PBSC)**                     | Bikeshare availability                                                                                                              | Per-feed (attribution-only)                                                                                                                                                                                                                                                                                                                           | Credit the operator (e.g. Austin BCycle) + its `license_url`                                                                                                   |
 | **Bike Share Toronto** (`toronto.publicbikesystem.net`) | Bikeshare station availability, Toronto | Operator GBFS feed. No licence is published: the City's open-data package declares none and the feed has no `license_url`. Attribution is given to the operator. | "Bike Share Toronto (Toronto Parking Authority)" |
 | **Bike Itaú / Tembici** (`*.publicbikesystem.net`, seven Brazilian cities, Santiago and Bogotá) | Bikeshare station availability: São Paulo, Rio de Janeiro, Salvador, Recife, Porto Alegre, Brasília, Curitiba, Santiago de Chile and Bogotá | Operator GBFS feeds. No licence is published: the feeds' `system_information.json` carries no `license_url`, operator or attribution fields. Attribution is given to the operator. | "Bike Itaú (Tembici)"; "Tembici Bogotá" |
@@ -167,7 +167,7 @@ The optional Local ADS-B layer and the broadcast-FM receiver use radio you recei
 - **Statens vegvesen road cameras.** Keyless. The camera list is one GeoJSON request to the OGC API Features view of the official DATEX 3.1 CCTV site table (`ogckart-sn1.atlas.vegvesen.no/ogc/features/v1/collections/datex_3_1:CctvSimple/items`), so no DATEX account is needed; frames are stills on `kamera.atlas.vegvesen.no/api/images/<cameraId>`, and only that exact path per camera is registered. Cameras the feed reports as faulty are dropped. About 135 working cameras also publish live HLS (`kamera.vegvesen.no/public/<cameraId>/manifest.m3u8`, MPEG-TS); those play as live video through the bounded in-memory HLS relay, with the still as the snapshot fallback, and only that exact manifest path per camera is registered. `CCTV_VEGVESEN_VIDEO=0` keeps every camera on stills. `orientationDescription` names the place a camera faces, not a bearing, so it goes into the label and headings use the id-hash fallback at low confidence. By default every live camera loads (~850); `CCTV_VEGVESEN_MAX_SOURCES` (8–1000) lowers the cap, keeping the cameras nearest Oslo, Bergen, Stavanger, Trondheim, Kristiansand, Bodø and Tromsø and `CCTV_VEGVESEN_ENABLED=0` turns the pack off. Frames are fetched at request time and never stored or redistributed. The NLOD attribution is registered in the Data attribution popover.
 - **NYC DOT Traffic Management Center cameras.** Off by default. NYC DOT's [developer data feeds page](https://www.nyc.gov/html/dot/html/about/datafeeds.shtml) asks developers who want the camera feed to contact `[email protected]` and sign a data-sharing agreement. This project does not hold one that covers downstream installations, so the pack loads only when an operator who holds their own agreement sets `CCTV_NYC_ENABLED=1`; with the flag unset, empty or any other value, the server makes no request to NYC DOT. The endpoint needs no key. The camera list is the public `webcams.nyctmc.org/api/cameras` catalog (~980 cameras across the five boroughs); frames are stills at `webcams.nyctmc.org/api/cameras/<uuid>/image`, synthesized from a validated UUID rather than taken from the payload, and only that host is registered. Cameras the feed reports as offline are dropped. The catalog publishes no camera facing, so headings use the shared id-hash fallback at low confidence and are corrected with the in-app calibration gizmo. Once enabled, the 250 cameras nearest the borough cores load; `CCTV_NYC_MAX_SOURCES` (8–400) changes the cap. Frames are fetched at request time and never stored or redistributed. NYC DOT asks every application that uses its data to carry its disclaimer; it is registered verbatim in the Data attribution popover.
 - **City of Toronto RESCU cameras.** Keyless. The camera list is the City's public `tmcearthcameras.json` on `opendata.toronto.ca` (dataset "Traffic Cameras", Transportation Services), served as JSONP and unwrapped with an anchored pattern. This is the municipal network the Ontario 511 pack does not carry: downtown arterials plus the Gardiner, DVP, Allen and Lake Shore. The list publishes no frame URL, so frame URLs are BUILT from the documented `CameraImages/loc####.jpg` convention and a strictly-digits camera number, pinning the frame proxy to the portal origin by construction; the list fetch refuses redirects and bounds the body it buffers. Frames are fetched at request time and never stored or redistributed. The dataset publishes no camera facing: the `D1`-`D4` fields are the directions of the *comparison* images (static reference stills captured in 2016 under a different path), not a bearing for the live pan-tilt-zoom frame, so headings use the shared id-hash fallback at low confidence and are corrected with the in-app calibration gizmo. A camera that is temporarily out of service still answers 200 with a byte-identical "Image Unavailable" placeholder rather than an error (about 6% of the network at any moment), so such a camera reads as healthy; the frame it shows is the agency's, not a synthesized one. The licence requires the attribution statement above. Disable with `CCTV_TORONTO_ENABLED=0`.
-- **Houston TranStar cameras.** Keyless. The camera list is the public `traffic.houstontranstar.org/data/layers/cctvSnapshots_json.js` catalog (~1,000 cameras across Greater Houston); frames are stills at `www.houstontranstar.org/snapshots/cctv/<id>.jpg`, synthesized from a validated numeric id rather than taken from the payload, and only that host is registered. Cameras whose catalog id is `0` (a different, non-snapshot class) and cameras outside Greater Houston are dropped. Dedicated `dir` values (North/South/East/West) become high-confidence headings; `None` uses the shared id-hash fallback at low confidence. By default the 250 cameras nearest downtown, Uptown, the Medical Center, IAH and Galveston load; `CCTV_HOUSTON_MAX_SOURCES` (8–400) changes the cap and `CCTV_HOUSTON_ENABLED=0` turns the pack off. Frames are fetched at request time and never stored or redistributed.
+- **Houston TranStar cameras.** Keyless. The camera list is the public `traffic.houstontranstar.org/data/layers/cctvSnapshots_json.js` catalog (~1,000 cameras across Greater Houston); frames are stills at `www.houstontranstar.org/snapshots/cctv/<id>.jpg`, synthesized from a validated numeric id rather than taken from the payload, and only that host is registered. Cameras whose catalog id is `0` (a different, non-snapshot class) and cameras outside Greater Houston are dropped. Dedicated `dir` values (North/South/East/West) become high-confidence headings; `None` uses the shared id-hash fallback at low confidence. TranStar's disclaimer is not a licence to ship the stills on by default (its FAQ grants permission-free use only for the RSS feeds), so the pack stays off unless `CCTV_HOUSTON_ENABLED=1`. Opting in loads the 250 cameras nearest downtown, Uptown, the Medical Center, IAH and Galveston; `CCTV_HOUSTON_MAX_SOURCES` (8–400) changes the cap. Snapshots update about every 3 minutes, which is also the ambient still cadence. Frames are fetched at request time and never stored or redistributed.
 - **Camera frame content.** Public camera frames can contain people, vehicles and license plates, and the camera layer does nothing with them beyond putting them on the map. A successful upstream response is relayed as the provider served it: nothing in the camera pipeline blurs, redacts, enhances or restores it, and nothing there runs face, plate or object detection or otherwise recognises or classifies what is in the picture. (The ALPR layer described below maps where plate-reader cameras are, from locations contributors tagged in OpenStreetMap; it reads nothing from any camera frame.) When an upstream has no frame for a camera, what you see instead is a Google Street View still or the app's own placeholder card; the panel's source badge names which of them you are looking at, and a refresh that fails after a frame has arrived leaves the last good picture on screen rather than replacing it. The browser resamples each frame for display: onto a fixed 1920x1080 surface for the camera's projection plane in the scene, and onto a 192x108 canvas for the small ambient card. That scaling is the only change made to the picture, and the only pixels the camera layer reads back are a 64x36 downscale hashed to tell whether the picture has changed. Live streams are piped through; the still path reads the image into memory to pass it on — TxDOT wraps its JPEG in a JSON envelope, which is decoded there — and no frame is written to disk (the disk cache, `.gev-cache/`, holds feed JSON for other layers and never camera imagery). Outside that pipeline, the voice assistant is the one feature that sends imagery anywhere: when it answers a question about what is in view it may attach a downscaled screenshot of the rendered scene — including any camera plane on screen — to the request it sends to the voice model. Frames are fetched only from server-registered camera URLs — a client cannot hand the proxy a URL (see [SECURITY.md](SECURITY.md)). What the app does stays inside the line README draws: no named-person search, no face recognition, no tracking individuals.
 - **Transit (GTFS-Realtime).** The proxy requests only registered operator feeds, validates redirects, bounds responses, and uses conditional requests, short snapshot caching and failure backoff. All sixteen registered regions are live-enabled; each can be disabled independently. Vehicles use delayed playback between reports, with report age and waiting states shown separately. Session-local selected trails are available for every feed. MBTA additionally retains up to 15 minutes of recently observed positions in the running proxy, so available history can survive a browser reload; server restart clears it. History reads never fetch upstream, and other feeds have no proxy retention. Nothing is archived to disk or collected in the background. Operator text credits are included as a courtesy and do not imply endorsement. Heights are aligned to work with Google 3D tiles; subway markers are shown at street level because these feeds do not supply depth. The TTC feed is BusTime, the surface system: it carries buses and streetcars and no subway at all. About four in ten of its vehicles report no route at all (unassigned or deadheading), and those are shown with the feed default rather than a route-established mode. It sends no ETag or Last-Modified, so its conditional requests fall through to the ordinary snapshot cache. Three Golden Horseshoe neighbours run alongside it — MiWay, Hamilton HSR and Durham Region Transit — each bus-only and each polled only near its own region. Durham Region Transit publishes no bearing on any vehicle, so those sprites take their heading from observed movement like any other feed that omits it. Guelph, Kingston and Barrie extend the same pattern eastward and north. Hamilton, Guelph, Burlington and YRT publish route ids that are not the number on the vehicle, so those entries carry a route-name table taken from each operator’s own published GTFS; any id missing from a table renders unchanged rather than blank. A label is never invented: YRT runs a route `9101` that appears nowhere in its published routes, so it stays as the feed sends it. Burlington’s is the one that cannot be shortcut: `351` is route 1 while `3510` is route 10, so the table is a real join rather than a trimmed prefix. GO Transit / Metrolinx is deliberately absent: its REALTIME feed requires an API key issued by manual review, which the keyless admission rule excludes (its static schedule download is keyless, but carries no vehicle positions). Barrie and YRT/Viva each invite acceptance of their licence through a form, and each licence also states that using the data is itself acceptance; this deployment relies on that clause, which is recorded in both entries. Grand River Transit in Waterloo is absent for a different reason: it answers, but its feed header was months stale and it publishes no per-vehicle timestamps, so it would render vehicles that look live and are not. Ottawa’s OC Transpo falls to the same keyless admission rule as GO Transit — its realtime feed requires an API key. London Transit and Thunder Bay Transit publish vehicle positions over plain HTTP with no HTTPS endpoint available. Every other Ontario system — Brampton, Oakville, Niagara, Milton, Windsor, Greater Sudbury, UP Express and a dozen smaller operators — publishes static GTFS schedules only, with no realtime vehicle positions to register. Between the nine included and these exclusions, every Ontario realtime vehicle-position feed catalogued in the Mobility Database is accounted for.
 - **Radio Browser.** `/api/radio/stations` discovers official API mirrors, makes bounded and coalesced healthy/geolocated HTTPS-station queries, caches the normalized public-domain directory for 45 minutes, and may serve the last good catalog for up to seven days during an outage. Refreshes must meet minimum accepted-query and station coverage before replacing a warm catalog; schema-valid responses whose rows all fail the product's health policy do not count as successful queries. A usable partial cold catalog is explicitly `DEGRADED`, and malformed or empty successful payloads are rejected atomically. Every directory and click-count request rejects redirects, validates all resolved addresses as globally routable (including reserved/documentation IPv4 and special/non-global IPv6 exclusions), and pins the TLS connection to a validated address. Only MP3/AAC non-HLS directory rows with public HTTPS stream targets are returned; favicons are intentionally omitted. Pressing play connects one browser audio element directly to the selected broadcaster and calls the directory's click counter through known-ID-only `POST /api/radio/click/:uuid`. GEV never proxies, caches, records, bundles, or redistributes audio. Radio Browser supplies station-level tags, not dependable current-song or upcoming-program metadata, so Radio filtering never claims either. Direct playback exposes the listener's IP address to the broadcaster, whose own stream terms apply.