fix(cctv): back off the Taiwan catalog when unreachable; review fixes

- taiwan.js: a failed download serves the last good table (up to 24 h)
  and is not retried for an hour. The table host does not answer from
  some networks outside Taiwan, and each attempt held the shared catalog
  refresh for the ~10 s connect timeout.
- Own server/providers/cctv/taiwan.js in package-boundaries.json
  (check:boundaries failed).
- Decode numeric character references; name falls back to the CCTVID
  when a row has no road details.
- Credit names the dataset and links the OGDL Taiwan licence.
- Document CCTV_TAIWAN_URL; list Taiwan in the CURRENT-STATE source table.
- Tests: isolate catalog env, reset loader state, cover the byte cap,
  failed fetch, backoff, last-good fallback, cap clamping, redirect with
  a valid body, name fallback, numeric entities and UUID camera ids.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

DATA_SOURCES.md

@@ -112,7 +112,7 @@ The optional Local ADS-B layer and the broadcast-FM receiver use radio you recei
   **Quebec is thinly represented**, and that is upstream rather than a filter here: the province runs its own Info-Smog program, so only a handful of Quebec stations appear in ECCC's national feed. The reporting station count also varies hour to hour as stations report or fall silent.
 
 - **Via Lietuva / Eismoinfo (Lithuania).** Public road-camera catalogs and periodically updated still images from [Eismoinfo](https://eismoinfo.lt/), credited to Via Lietuva / eismoinfo.lt in the app. **Off by default.** The camera endpoints are the eismoinfo.lt website backend and are not among the services listed in Via Lietuva's [open-data statement](https://eismoinfo.lt/eismoinfo-backend/content?id=44), whose conditions are attribution and reuse on the same terms. Until the statement is confirmed to cover the camera photos, the pack loads only when an operator sets `CCTV_LITHUANIA_ENABLED=1`; with the flag unset, empty or any other value, the server makes no request to Eismoinfo. `eismoinfo-backend/camera-info-table` is joined by ID to `layer-static-features/VKR`. Without `lks=true`, the latter returns WGS84 `[latitude, longitude]`; the table's `x/y` instead use LKS-94 metres. Only the official HTTPS `/eismoinfo-backend/image-provider/camera/last?id=…` image endpoint is registered. Catalogs use the shared 15-minute cache; frames are fetched on demand and never bundled or archived. These are periodic snapshots, not continuous video. Camera headings are low-confidence estimates. No API key is required. `CCTV_LITHUANIA_MAX_SOURCES` defaults to 400.
-- **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 with attribution; the app credits the Freeway Bureau, MOTC. 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. On by default; `CCTV_TAIWAN_ENABLED=0` skips the pack, and `CCTV_TAIWAN_MAX_SOURCES` defaults to 600 (bounded to 1–2000).
+- **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)).
 - **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.