The page draws the camera from /camera/<id>/ws when relayed and reconnects after 2 s without a frame #140

Part of #87, the browser half. Pull #103's src/ui/video.js may be taken from there.

Done:

• [ ] The camera code moves from viewer.html into Software/so101/src/ui/video.js, loaded by dynamic import so the first visit stays under the existing 50 KB test. When relayed, it draws frames from the socket; with no frame for 2 s, it reconnects.
• [ ] The <img src=/camera/<id>/stream> path stays only for the local (non-relayed) case.
• [ ] src/ui/video.test.ts covers the reconnect timer and the local/relayed choice. bun --cwd Software/so101 test passes, including the first-visit size test.