fix: duplicate boardContainer declaration crashing entire app

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

public/js/modules/chess/scenes/game.js

@@ -150,10 +150,10 @@ export function mountGame(el, params) {
   }
 
   // Emote system
-  const boardContainer = el.querySelector('#board-container');
-  emoteSystem.create(boardContainer, (emote) => {
+  const emoteContainer = el.querySelector('#board-container');
+  emoteSystem.create(emoteContainer, (emote) => {
     audio.play('notification');
-    emoteSystem.showReceived(boardContainer, emote.emoji);
+    emoteSystem.showReceived(emoteContainer, emote.emoji);
   });
 
   bus.emit('game:started', { gameKey: 'chess', matchId, opponent: botId, mode });