The relay serves /camera/<id>/video from ARM_H264_<n> sources, flags h264 in /cameras, and allows the Pi's H.264 ports in egress #259

From #70, piece 3 of 4. It builds on the fanout module. Take the code from pull #207's branch smith/70-real-video-hardware-h-264-from-the-pi-ov; three reviews accepted its design, caps, security and fallback.

Done:

• [ ] src/video-feed.ts fetches each configured rendition through proxyFor (egress), and src/relay.ts parses ARM_H264_<n> (720p=url,480p=url,…) and serves WS /camera/<id>/video same-origin, offering only the rungs that have a source. GET /cameras gains h264 per camera. bench/fake-serve.ts wires it in.
• [ ] forge.json egress adds 100.89.95.68:8082, :8083 and :8084, and the README documents the variable, the ladder and the egress ports.
• [ ] src/relay-video.test.ts and src/video-feed.test.ts (from the branch) pass: a cross-origin upgrade is refused, a camera with no source is refused, and a guest gets frames. bun --cwd Software/so101 test passes.