ROOT CAUSE: Supabase RLS on matchmaking_queue only allowed players to
see their OWN rows. Player A couldn't find Player B in the queue.

FIX: All matchmaking operations now use service_role key (bypasses RLS):
- handleQueue: searches ALL waiting players, not just own
- handleStatus: reads match details with service key
- handleDequeue: cleans up with service key
- Random color assignment (50/50 white/black)

Chess game live mode:
- NEW: sendLiveMove() — sends current FEN + move_count to server after player moves
- NEW: startLivePolling() — polls match row every 2s for opponent's move
- NEW: When opponent's move_count increases, loads new FEN and updates board
- NEW: Detects opponent resign/completion via status field
- If playing as black in live mode, waits for white's first move
- stopLivePolling() on game end

Flow:
1. Player A queues → inserted as 'waiting'
2. Player B queues → finds Player A, creates match, marks A as 'matched'
3. Player B gets match_id immediately (they're white or black randomly)
4. Player A polls status → finds 'matched' → gets match_id + color
5. Both enter chess-game with mode:'live' + matchId
6. Each player's moves update the match row
7. Opponent detects new move_count via polling
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>