Fix game.started not firing when Jackbox room is full

The waitForGameStart() function checked roomStatus.full before
roomStatus.locked, causing it to short-circuit when a room was full
but the game hadn't started yet. This meant game.started was never
broadcast and watchGameAsAudience() was never called for full games.

Now only locked=true triggers game start detection. When full=true
but locked=false, the poller continues until the game actually starts.

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

backend/utils/player-count-checker.js

@@ -406,24 +406,20 @@ async function startPlayerCountCheck(sessionId, gameId, roomCode, maxPlayers = 8
       return false;
     }
 
-    // If full, we know the count immediately
-    if (roomStatus.full) {
-      console.log(`[Player Count] Room is FULL - ${roomStatus.maxPlayers} players`);
-      updatePlayerCount(sessionId, gameId, roomStatus.maxPlayers, 'completed');
-      stopPlayerCountCheck(sessionId, gameId);
-      return false;
-    }
-
     // If locked, game has started - ready to watch
     if (roomStatus.locked) {
       console.log(`[Player Count] Room is LOCKED - game in progress, starting watch`);
-      // Return both status and real maxPlayers from Jackbox
       return { ready: true, maxPlayers: roomStatus.maxPlayers };
     }
 
-    // Not ready yet
+    // Log if full but not yet started
+    if (roomStatus.full) {
+      console.log(`[Player Count] Room is FULL but not locked yet - waiting for game start`);
+    } else {
       console.log(`[Player Count] Room not ready yet (lobby still open)`);
-    return null;
+    }
+    
+    return null; // Not ready, keep polling
   };
 
   // Wait 10 seconds before first check