fix: edge case bugs + toggle lyrics from player bar and lyrics button

Bugs fixed:
- play-at: stop current playback before jumping to queue index
- playNext retry: use break instead of return to ensure stateChange emits
- sendVoiceData: skip if disconnecting to avoid errors during teardown

UI: player-left and lyrics button now toggle lyrics page (open/close)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/bot/instance.ts

@@ -491,7 +491,7 @@ export class BotInstance extends EventEmitter {
           for (let i = 0; i < 3; i++) {
             const retry = this.queue.next();
             if (!retry) break;
-            if (await this.resolveAndPlay(retry)) return;
+            if (await this.resolveAndPlay(retry)) break;
           }
           this.player.stop();
         }