feat(cctv): King County road camera source pack (Washington State)

Adds King County DOT Road Services' cameras as a keyless source pack, from
the county's public ArcGIS FeatureServer layer ("King County and WSDOT
Traffic Cameras"). 59 live cameras against the current feed.

- The `outFields` list is explicit on purpose: the layer also carries
  asset-administration columns (including staff names) that must never be
  fetched.
- Only live, active cameras with frames on the county's own
  info.kingcounty.gov image handler are registered; the feed writes http://
  and the handler serves HTTPS, so URLs are upgraded and pinned before
  registration. WSDOT-owned rows are skipped so a camera never appears twice
  when a statewide WSDOT pack is present; the few city-owned cameras the
  county hosts (Redmond, Sammamish, Newcastle, Snoqualmie) carry their owner
  as the per-camera credit, DriveBC-style.
- The layer publishes no facing: headings use the shared id-hash fallback at
  low confidence, correctable with the calibration gizmo.
- Uniquely among the packs, the county publishes each camera's hardware
  Manufacturer/Model (Cohu 3950/3965, Bosch AUTODOME IP 5000i, Axis
  Q6135-LE, Siqura PD910). The model string is whitespace-collapsed (the
  feed carries stray newlines) and carried on the source as `model`, with an
  additive passthrough in normalizeSourceItem (same pattern as poseSource)
  so identified-hardware consumers can use it. All 59 live cameras carry a
  model value.
- Attribution per the KCGIS Center terms, registered in the attribution
  popover and documented in DATA_SOURCES.md.
- Defaults: the whole catalog loads (125 cap); CCTV_KINGCOUNTY_MAX_SOURCES
  changes the cap, CCTV_KINGCOUNTY_ENABLED=0 turns the pack off.
- Tests: filtering (owner/live/status/host/geometry/bbox), HTTPS upgrade,
  model whitespace-collapse and passthrough, partner-city credit, env cap,
  upstream-failure fallback, and normalizeSourceItem model semantics.

DATA_SOURCES.md

@@ -55,6 +55,7 @@ How to read this:
 | **Fintraffic / Digitraffic (weathercams)**                            | CCTV camera catalog + frames, Finland                                                                                               | [CC BY 4.0](https://www.digitraffic.fi/en/terms-of-service/) — attribution REQUIRED                                                                                                                                                                                                                                                                   | "Fintraffic / digitraffic.fi, license CC BY 4.0"                                                                                            |
 | **DriveBC** (Government of British Columbia)                          | CCTV camera catalog + frames, British Columbia highways                                                                             | [Open Government Licence – British Columbia](https://www2.gov.bc.ca/gov/content/data/open-data/open-government-licence-bc) — attribution REQUIRED                                                                                                                                                                                                     | "DriveBC. Contains information licensed under the Open Government Licence – British Columbia"                                               |
 | **Open Calgary** (`data.calgary.ca`)                                  | CCTV camera catalog + frames, Calgary                                                                                               | [Open Government Licence – City of Calgary](https://data.calgary.ca/stories/s/Open-Calgary-Terms-of-Use/u45n-7awa) — attribution REQUIRED                                                                                                                                                                                                             | "Contains information licensed under the Open Government Licence – City of Calgary"                                                         |
+| **King County Road Services** (`services.arcgis.com`, King County GIS) | CCTV camera catalog + frames, unincorporated King County WA road network                                                            | [KCGIS Center terms](https://kingcounty.gov/en/dept/kcit/data-information-services/gis-center/about/terms-conditions-copyrights) — attribution required; public ArcGIS layer                                                                                                                                                                          | "King County Road Services" (partner-city cameras name their owner)                                                                         |
 | **GBFS (Lyft / BCycle)**                                              | Bikeshare availability                                                                                                              | Per-feed (attribution-only)                                                                                                                                                                                                                                                                                                                           | Credit the operator (e.g. Austin BCycle) + its `license_url`                                                                                |
 | **MBTA / MassDOT** (cdn.mbta.com) | Transit layer live vehicles and up to 15 minutes of recently observed positions, Greater Boston | MBTA / MassDOT open realtime vehicle data, used for the live view and up to fifteen minutes of recently observed positions; published for developer use and not against their use. | Attribution to MBTA / MassDOT (courtesy text) |
 | **CapMetro** (data.texas.gov) | Transit layer live vehicles, Austin TX | CapMetro open realtime vehicle data, used for the live view; published for developer use and not against their use. | Attribution to CapMetro (courtesy text) |
@@ -89,6 +90,7 @@ The optional Local ADS-B layer and the broadcast-FM receiver use radio you recei
 - **Warendorf webcam.** The Stadt Warendorf Marktplatz webcam, registered from the curated `config/cctv_sources.warendorf.json` (the Kreis Warendorf registration-office cameras from the contributing PR are indoor waiting rooms and were left out); only the municipal image host is proxied, frames are fetched at request time and never stored or redistributed. Disable with `CCTV_WARENDORF_ENABLED=0`.
 - **Live Traffic NSW cameras.** The camera list is the keyless public `data.livetraffic.com/cameras/traffic-cam.json` feed (Transport for NSW open data, CC BY 4.0); frames are stills on `webcams.transport.nsw.gov.au`, and only that host is registered. That image host answers non-browser clients with an HTML placeholder, so the proxy identifies as a browser for that one host and as itself everywhere else. Frames are fetched at request time and never stored or redistributed. Disable with `CCTV_NSW_ENABLED=0`.
 - **Open Calgary traffic cameras.** Keyless. The camera list is the public Socrata dataset `k7p9-kppz` on `data.calgary.ca`; frames are stills on the city's own `trafficcam.calgary.ca` host, and only that host is registered. Most rows publish an `http://` frame URL and the host redirects those to HTTPS, so URLs are upgraded and pinned to that origin before registration. Frames are fetched at request time and never stored or redistributed. The dataset publishes no camera facing: the `quadrant` field and the quadrant suffix on each camera name are Calgary's address grid, not a bearing, so headings use the shared id-hash fallback at low confidence and are corrected with the in-app calibration gizmo. The licence requires the attribution statement above. Disable with `CCTV_CALGARY_ENABLED=0`.
+- **King County road cameras.** Keyless. The camera list is one public ArcGIS FeatureServer GeoJSON query (King County DOT Road Services, "King County and WSDOT Traffic Cameras"). The `outFields` list is explicit on purpose: the layer also carries asset-administration columns — including staff names — that are never fetched. Only live, active cameras with frames on the county's own `info.kingcounty.gov` image handler are registered (the feed writes `http://`; the handler serves HTTPS, so URLs are upgraded and pinned before registration). WSDOT-owned rows in the layer are skipped so a camera never appears twice when a statewide WSDOT pack is present; the few city-owned cameras the county hosts (Redmond, Sammamish, Newcastle, Snoqualmie) carry their owner as the per-camera credit. The layer publishes no facing, so headings use the shared id-hash fallback at low confidence. Uniquely, the county publishes each camera's hardware `Manufacturer`/`Model` (Cohu 3950/3965, Bosch AUTODOME, Axis PTZ domes); the model string is carried on the source as `model` for identified-hardware consumers. Frames are fetched at request time and never stored or redistributed. Disable with `CCTV_KINGCOUNTY_ENABLED=0`.
 - **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 seven 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.
 - **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.