GET /sites
GET /cameras
GET /sites/{site_id}/cameras
GET /whep-link/{site_id}/{camera_id}
POST /whep/{site_id}/{camera_id}
WS /ws/{site_id}/{camera_id}?fps=N
click Start to fetch /whep-link and run WebRTC
/ws/{site}/{cam}?fps=N — frames arrive as JPEG bytes