Merge PR #489 live CCTV onto current architecture

SECURITY.md

@@ -62,6 +62,7 @@ browser-key fallback for existing single-key setups.
 The data proxies under `server/providers/` are written so the browser cannot turn the server into an open relay:
 
 - **No arbitrary-URL fetching.** The CCTV frame proxy fetches only server-registered camera/frame URLs — clients cannot pass an upstream URL to fetch (SSRF mitigation). Other proxies target fixed upstream hosts.
+- **Live video stays origin-pinned.** `/api/cctv/media/<id>/…` sub-paths resolve only against the registered camera's origin; a playlist reference or segment that would resolve elsewhere is refused. Segment stores live under the OS temp dir, keyed by a sanitized camera id, and are pruned to a fixed window and reaped when idle. When ffmpeg is present it is spawned only with a registered camera URL as input — never anything supplied by a client.
 - **Radio is not an audio relay.** `/api/radio/stations` contacts only allowlisted Radio Browser HTTPS hosts and paths, rejects redirects, rejects any hostname with a loopback/private/link-local/metadata/non-public A or AAAA result, and pins each TLS connection to a validated address. It returns normalized public HTTPS stream URLs; `/api/radio/click/:uuid` applies the same destination policy and accepts only station IDs from the current bounded catalog. The browser then connects directly to the broadcaster after an explicit playback action, so the broadcaster sees the listener's IP address. GEV never proxies, caches, records, or redistributes audio.
 - **No verbatim client headers upstream.** The CCTV media route is the one route that relays a request header (`Range`, for video seeking). It is parsed and canonicalized before it is forwarded: one `bytes=` range only, with every accepted form — explicit span, open-ended and suffix — bounded to the same 64 MiB ceiling the relay applies to a declared response body. Multi-range, malformed, inverted and non-`bytes` values are dropped and the request proceeds without a `Range`, as RFC 7233 §3.1 prescribes. Bounding the request bounds what is asked for: a response that declares no length — live streamed media, or a chunked body from an upstream that ignores the `Range` — has no ceiling. An upstream request the browser has stopped waiting for is cancelled rather than left running, whether the viewer leaves before the headers arrive or during the body.
 - **Response-size caps and timeouts** on proxied responses.