fix: detect game start for Pack 7+ titles that don't use state: "Gameplay"

Pack 7 games (Quiplash 3, Blather Round) transition room state from
"Lobby" to "Logo" instead of "Gameplay". Even newer titles (Doominate,
Big Survey) have no room entity at all — the only signals are room/lock
and room/exit opcodes.

- parseRoomEntity: detect game started as any non-Lobby state
- handleMessage: add room/lock and room/exit opcode handling
- handleRoomLock: emit game.started as fallback for room-entity-less games
- handleRoomExit: emit game.ended on explicit room close
- Tests: 6 new tests covering Logo state, room/lock, room/exit

Verified against live rooms: quiplash3, blanky-blank, you-ruined-it,
bigsurvey.

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

backend/utils/ecast-shard-client.js

@@ -36,7 +36,7 @@ class EcastShardClient {
       lobbyState: roomVal.lobbyState ?? null,
       gameCanStart: !!roomVal.gameCanStart,
       gameIsStarting: !!roomVal.gameIsStarting,
-      gameStarted: roomVal.state === 'Gameplay',
+      gameStarted: roomVal.state != null && roomVal.state !== 'Lobby',
       gameFinished: !!roomVal.gameFinished,
     };
   }
@@ -213,6 +213,12 @@ class EcastShardClient {
         break;
       case 'client/disconnected':
         break;
+      case 'room/lock':
+        this.handleRoomLock();
+        break;
+      case 'room/exit':
+        this.handleRoomExit(message.result);
+        break;
       case 'error':
         this.handleError(message.result);
         break;
@@ -363,6 +369,44 @@ class EcastShardClient {
     }
   }
 
+  handleRoomLock() {
+    if (!this.gameStarted) {
+      console.log(`[Shard Monitor] Room ${this.roomCode} locked (game starting)`);
+      this.gameStarted = true;
+      this.gameState = this.gameState || 'Gameplay';
+      this.onEvent('game.started', {
+        sessionId: this.sessionId,
+        gameId: this.gameId,
+        roomCode: this.roomCode,
+        playerCount: this.playerCount,
+        players: [...this.playerNames],
+        maxPlayers: this.maxPlayers,
+      });
+    }
+  }
+
+  handleRoomExit() {
+    if (this.gameFinished) return;
+    console.log(`[Shard Monitor] Room ${this.roomCode} exited`);
+    this.gameFinished = true;
+    this.onEvent('game.ended', {
+      sessionId: this.sessionId,
+      gameId: this.gameId,
+      roomCode: this.roomCode,
+      playerCount: this.playerCount,
+      players: [...this.playerNames],
+    });
+    this.onEvent('room.disconnected', {
+      sessionId: this.sessionId,
+      gameId: this.gameId,
+      roomCode: this.roomCode,
+      reason: 'room_closed',
+      finalPlayerCount: this.playerCount,
+    });
+    activeShards.delete(`${this.sessionId}-${this.gameId}`);
+    this.disconnect();
+  }
+
   handleError(result) {
     console.error(`[Shard Monitor] Ecast error ${result?.code}: ${result?.msg}`);
     if (result?.code === 2027) {