- TestStatsEndpoint: empty bridge stats, stats after activity
- TestGoCommand: room change, occupant tracking, old-room notification,
same-room rejection, missing room argument
- TestEmoteCommand: room broadcast, first-person response, no self-echo,
/me alias support
- Also fix bare 'go'/'move' (no argument) to show usage hint
- say <message> now queues room_broadcast events on other sessions
- New GET /bridge/room_events/{user_id} endpoint (drain-on-read)
- WS connections receive real-time room broadcasts
- 5 new tests: broadcast, no-echo, room isolation, drain, 404
- Total tests: 27 (all passing)
