feat: add TMP3 support and fix shard probe lifecycle bug

Add Trivia Murder Party 3 (Playtest) ticker and seed data. Bind-mount
tickers.json in docker-compose so ticker changes take effect on restart
without image rebuilds.

Fix shard monitor probe poisoning game lifecycle state — the player-count
probe no longer sets gameFinished, which was preventing the main WS from
processing room/lock and room/exit for games like TMP3 that don't send
entity updates.

Co-authored-by: Cursor <cursoragent@cursor.com>

docker-compose.yml

@@ -17,6 +17,7 @@ services:
       - jackbox-data:/app/data
       - ./games-list.csv:/app/games-list.csv:ro,z
       - ./backend/config/admins.json:/app/config/admins.json:ro,z
+      - ./backend/config/tickers.json:/app/config/tickers.json:ro,z
     ports:
       - "5000:5000"
     networks: