Add WebRTC auto-reconnect for player and broadcaster

[sleroq]

Summary

• Add a shared reconnect controller hook with bounded exponential backoff, jitter, and cancel/reset controls.
• Implement viewer (WHEP) auto-reconnect on offline/disconnect paths and classify setup failures as retryable vs fatal.
• Implement broadcaster (WHIP) auto-reconnect on ICE/SSE/transient setup failures, and clean up stale WHIP sessions via DELETE on replace/unmount.

[Sean-Der]

@sleroq This is great! Will be nice for server restarts, right now it's pretty painful.

WebRTC should reconnect automatically on ICE failures, I should make sure that is working ok. WHIP also has ICE Restarts so you can keep one WebRTC connection and keep re-using it. I try to lean into the WebRTC native stuff as much as possible (so OBS/FFmpeg/GStreamer/Mobile clients) get the benefits not just web.

Keep up the great work :)