feat: MCP Unity 场景优化 — 完整交互体系搭建

- 删除重复 Ground
- 创建 [Managers] 空物体，挂载 GameManager + StepManager + ExperimentFlowCoordinator + AudioManager
- Main Camera 挂载 InteractionSystem
- 伤者 InjectedPerson 下创建 5 个交互子物体 (InjuryVisual/Swelling/Pain/VitalSigns/Neuro)
- 创建绑带位置、踝关节、衬垫、夹板位置等空物体
- 道具摆放到位：伤者(2,0.05,5) 施救者(3,0,5) 鞋(2.7,0.15,5.5) 绷带/夹板/急救箱在旁
- InjuryLeg Tag 修正，Ground Tag 修正
- 全部新脚本同步导入 (ExperimentTypes/StepData/ExperimentConfig/StepManager/GameManager/ExperimentFlowCoordinator/InteractionSystem/DraggableObject/HighlightEffect/UIManager/ExamPopup/ScoreDisplay/VideoController/AudioManager/CharacterAnimController/StepAnimationHandler)
- 旧脚本 (ExperimentController/ConfigLoader/AnimationController/HUDController/VideoPlayerController/PopupSystem/ModeSelectionUI) 全部兼容修复或 stub
- 编译通过，0 错误
- Canvas 挂载 UIManager

ProjectSettings/EditorBuildSettings.asset

@@ -6,6 +6,12 @@ EditorBuildSettings:
   serializedVersion: 2
   m_Scenes:
   - enabled: 1
-    path: Assets/Scenes/SampleScene.unity
+    path: Assets/Scenes/main.unity
     guid: 99c9720ab356a0642a771bea13969a05
+  - enabled: 1
+    path: Assets/Scenes/ModeSelection.unity
+    guid: cffb0242a91904c5986f45e78b1820b3
+  - enabled: 1
+    path: Assets/Scenes/Experiment.unity
+    guid: a37b51f5c4beb4b4398199d197af7d37
   m_configObjects: {}

ProjectSettings/TagManager.asset

@@ -3,7 +3,15 @@
 --- !u!78 &1
 TagManager:
   serializedVersion: 2
-  tags: []
+  tags:
+  - InjuredPerson
+  - Rescuer
+  - Shoe
+  - Bandage
+  - Splint
+  - FirstAidKit
+  - InjuryLeg
+  - Ground
   layers:
   - Default
   - TransparentFX