Step 2 of host control mode (server-side, fully testable without UI):
- Room now tracks hostPeerId (= first joiner) and controlMode ('everyone' default).
- ROOM_DATA carries hostPeerId + controlMode so clients know their role on join.
- SET_CONTROL_MODE handler: host-only authority check, broadcasts CONTROL_MODE.
- Relay gate: in host-only mode, drop room-moving events (play/pause/seek/
force-sync/episode-lobby) from non-host guests — robust chokepoint that kills
spam regardless of client. Heartbeats/ACKs/episode-ready still pass.
- removePeerFromRoom: if the host leaves, fall back to 'everyone' and reassign
host to the earliest remaining peer (v1: immediate, no grace period).
Extends the WS integration test suite to cover all of the above.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Tests: connect, room create/join, password auth, play/pause/seek relay,
force_sync, event_ack, episode_lobby, peer leave, ping/pong, room list,
protocol version check, deduplication, health HTTP endpoint.
All 13 tests pass as part of npm run verify.