fix: 提交正确答案时只播放成功音效，避免与点击音效重合

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

assets/prefabs/PageLevel.ts

@@ -648,8 +648,7 @@ export class PageLevel extends BaseView {
         console.log(`[PageLevel] 提交答案: ${userAnswer}, 正确答案: ${this._currentConfig.answer}`);
 
         if (userAnswer === this._currentConfig.answer) {
-            // 答案正确
-            this.playClickSound();
+            // 答案正确，只播放成功音效（不播放点击音效，避免重合）
             this.showSuccess();
         } else {
             // 答案错误