fix: restore peer connectivity, native-first playback, Fly.io config

feat(calls): native WebRTC mesh (drop PeerJS); faster transcode; deploy docs

fix: stop streams/calls breaking — remove regressions, add diagnostics

fix: smooth streaming, call reliability, joiner sync, and many UX bugs

fix: self-host PeerJS, repair subtitles/dedup, mobile responsiveness

Pre-buffer 5MB before stream, STUN servers for PeerJS, initial buffering state

Fix PeerJS (cloud broker), sync stream for new joiners, mobile responsive sidebar

Fix PeerJS: integrate into main HTTP server so it works on HF Spaces (single port)

Initial commit: WatchTorrent - synchronized torrent streaming app