Merge branch 'main' into feat/radio-country-coverage

DATA_SOURCES.md

@@ -98,6 +98,8 @@ How to read this:
 | **Burlington Transit** (opendata.burlington.ca) | Transit layer live vehicles, Burlington ON | Burlington Transit realtime data under the City of Burlington Open Data Terms of Use, which permit any lawful purpose. The terms are revocable and must travel with the data, so the credit links them. Route ids are internal keys and are joined to the City’s published GTFS. | Credit to the City of Burlington plus a link to its Open Data Terms of Use, which the licence requires |
 | **Radio Browser**                                                     | Geolocated internet-radio station directory and station-level tags                                                                  | Public-domain directory data under PDDL 1.0; individual broadcaster stream terms apply                                                                                                                                                                                                                                                                | "Radio Browser" plus a link to the selected broadcaster                                                                                     |
 | **Re:Earth Terrain** (Mapterhorn)                                     | Terrain (keyless globe stacks — OSM etc. — + `/api/terrain/heights` ellipsoidal-height lookups)                                     | Terrain mesh: CC BY 4.0; geoid: EGM2008 (NGA, public domain)                                                                                                                                                                                                                                                                                          | "Terrain (keyless globe stacks): Re:Earth Terrain / Mapterhorn (CC BY 4.0) / EGM2008 (NGA)"                                                 |
+| **OpenSeaMap** (`tiles.openseamap.org`) | Sea Marks layer: raster overlay of buoys, lighthouses and ports (#10) | Chart tiles CC BY-SA 2.0; data ODbL 1.0 via OpenStreetMap | "Sea marks © OpenSeaMap contributors (CC BY-SA 2.0) · Data © OpenStreetMap contributors (ODbL)" |
+| **OpenSnowMap** (`www.opensnowmap.org`) | Ski Pistes layer: raster overlay of ski runs and lifts (#10) | Tiles CC BY-SA; data ODbL 1.0 via OpenStreetMap; bulk tile download forbidden without prior agreement | "Ski pistes © www.opensnowmap.org (CC BY-SA) · Data © OpenStreetMap contributors (ODbL)" |
 | **OSRM on the FOSSGIS routing servers** (`routing.openstreetmap.de`) | Street-following routes for the Directions layer and voice route annotations, via `/api/route` | [FOSSGIS routing usage policy](https://routing.openstreetmap.de/about.html): "Display the required attribution and display a link to 'fix the map'", "Use a valid user agent and, if applicable, a correct referrer", "One request per second max", "No scraping, no heavy usage". The full policy is the German [FOSSGIS Nutzungsbedingungen](https://www.fossgis.de/arbeitsgruppen/osm-server/nutzungsbedingungen/); FOSSGIS also states that the server may be embedded in your own pages but "eine gewerbliche Nutzung ist nur mit Einschränkungen erlaubt" (commercial use only with restrictions). Route data derives from OpenStreetMap (ODbL 1.0) | "Routing: OSRM on the FOSSGIS servers" + a "fix the map" link — shown in the Data attribution popover |
 
 ### Local receiver input (not fetched from a service)
@@ -118,6 +120,7 @@ The optional Local ADS-B layer and the broadcast-FM receiver use radio you recei
 - **Freeway Bureau, MOTC (Taiwan).** National freeway cameras from the Freeway Bureau's keyless [CCTV static table](https://tisvcloud.freeway.gov.tw/history/motc20/CCTV.xml) in the MOTC 2.0 standard, refreshed daily and fetched at runtime (never bundled). Freeway Bureau traffic data is published under the [Open Government Data License, Taiwan (Version 1.0)](https://data.gov.tw/license), which permits reuse, including commercial reuse, with attribution; the app credits the Freeway Bureau, MOTC, names the dataset and links the licence, as its attribution exhibit asks. The table publishes each camera's MJPEG stream on one of four official camera servers (`cctvn`, `cctvn5`, `cctvc`, `cctvs` under `freeway.gov.tw`). The frame proxy relays single images, so each published stream URL is mapped to the same server's single-JPEG path for the same camera number (`/abs2mjpg/bmjpg` → `/abs2mjpg/jpg`, `/live-view/mjpg/video.cgi` → `/live-view/jpg/image.cgi`); only those exact HTTPS pairs are registered, and the still path is not itself listed in the table. These are on-demand snapshots, not continuous video. Camera headings are low-confidence estimates. No API key is required. The table host does not answer from some networks outside Taiwan (the camera servers do); there the pack is empty, logs one warning and retries hourly. On by default; `CCTV_TAIWAN_ENABLED=0` skips the pack, and `CCTV_TAIWAN_MAX_SOURCES` defaults to 600 (bounded to 1–2000).
 
 - **Google Maps Platform.** You supply your own API key and are bound by [Google's ToS](https://cloud.google.com/maps-platform/terms). Google Maps Content (tiles, geocodes, places) **may not be cached, stored, rehosted, or committed** — this app only ever uses it live, which is the compliant pattern. The "Google" attribution is displayed on the globe and must stay visible. Restrict your key (see [SECURITY.md](SECURITY.md)).
+- **Sea Marks and Ski Pistes (#10).** Two keyless raster overlay layers under Infrastructure, OpenSeaMap sea marks and OpenSnowMap ski pistes, requested tile by tile as the camera views them, with no prefetch, bulk download or caching on our side (OpenSnowMap forbids bulk tile download without prior agreement). They drape on the globe on the OSM and Bing stacks and on the Google Photorealistic tileset on Google 3D (see `src/maps/imageryHost.js`). OpenRailwayMap and OpenInfraMap, also requested in #10, are not included: OpenRailwayMap's tile server only answers requests whose Referer is its own site, and OpenInfraMap serves vector tiles that need a vector rendering pipeline.
 - **OpenSky Network.** Its license is **non-commercial**, and operational use of the REST API in a live product can require a prior written agreement with OpenSky — even for non-profit/government use. If you deploy this commercially, contact OpenSky for your own terms. The flights layer is a toggle and runs anonymously by default.
 - **adsb.lol flight fallback.** When OpenSky is unavailable and no last-good OpenSky response exists, the server requests a cached, capped 250 nm adsb.lol point snapshot around the current camera subpoint. This is regional observed context, not worldwide completeness; provenance is exposed in the Flights stats/context row. Military ICAOs remain reconciled through the existing dedicated military registry rather than duplicated.
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