feat: 音频系统重构 - bg音乐流程修复 + woman语音按点位播放

改动:
1. TouchPositionHandler新增voiceClip字段, 点击时播放对应语音
2. PageController.ShowPage: 首页播放homeBg
3. OnFixationSelected: StopBgMusic()(开场动画开始时停bg)
4. ActivateExperimentObjects: 移除PlayWomanAudioSequence, 保留PlayExperimentBg
5. 新增PlayHomeBg/StopBgMusic/PlayExperimentBg方法
6. 删除_audioManager冗余引用

流程:
首页→homeBg播 → 选固定方式→bg停 → 开场动画→实验bg播
woman语音1→点击point1播, 语音2→point2, 语音3→point3

Assets/Scripts/Interaction/TouchPositionHandler.cs

@@ -9,6 +9,7 @@ public class TouchPositionHandler : MonoBehaviour
     public Transform targetPosition;
     public GameObject womanObject;
     public GameObject nextTouchObject;
+    public AudioClip voiceClip;
 
     private MeshRenderer _meshRenderer;
 
@@ -37,7 +38,7 @@ public class TouchPositionHandler : MonoBehaviour
             womanObject.transform.position = targetPosition.position;
             womanObject.transform.rotation = targetPosition.rotation;
             Debug.Log($"[TouchPosition] woman 移动到 {targetPosition.name}");
-        }
+        if (voiceClip != null) { var asrc = gameObject.AddComponent<AudioSource>(); asrc.PlayOneShot(voiceClip); Debug.Log("[TouchPosition] 播放语音: " + voiceClip.name); }        }
 
         // 通知 StepManager 记录步骤
         int stepIndex = transform.GetSiblingIndex() + 1;