feat: 添加全局屏幕转场面板

- 新增 ScreenTransitionPanel，支持 fade_in/out、fade_in_white、flash_white、
  wipe_in/out、shutter_in/out 等多种转场效果
- 新增 Screen Transition Panel Prefab 并在 Persistence 场景挂载
- UIManager 启动时自动显示该面板
- BaseYarnCommand 新增对应的 Yarn 全局转场指令

Assets/Scenes/Persistence.unity

@@ -8385,6 +8385,7 @@ RectTransform:
   - {fileID: 923998313}
   - {fileID: 1867622714}
   - {fileID: 3100100002}
+  - {fileID: 3100101002}
   m_Father: {fileID: 1110722291}
   m_LocalEulerAnglesHint: {x: 0, y: 0, z: 0}
   m_AnchorMin: {x: 0, y: 0}
@@ -9687,6 +9688,24 @@ PrefabInstance:
     m_AddedGameObjects: []
     m_AddedComponents: []
   m_SourcePrefab: {fileID: 100100000, guid: 0bd336c33b9dc77498582232b543e604, type: 3}
+--- !u!1001 &3100101000
+PrefabInstance:
+  m_ObjectHideFlags: 0
+  serializedVersion: 2
+  m_Modification:
+    serializedVersion: 3
+    m_TransformParent: {fileID: 2091451641}
+    m_Modifications: []
+    m_RemovedComponents: []
+    m_RemovedGameObjects: []
+    m_AddedGameObjects: []
+    m_AddedComponents: []
+  m_SourcePrefab: {fileID: 100100000, guid: 3923593479c745bdb809777da8333e7e, type: 3}
+--- !u!224 &3100101002 stripped
+RectTransform:
+  m_CorrespondingSourceObject: {fileID: 100101, guid: 3923593479c745bdb809777da8333e7e, type: 3}
+  m_PrefabInstance: {fileID: 3100101000}
+  m_PrefabAsset: {fileID: 0}
 --- !u!1660057539 &9223372036854775807
 SceneRoots:
   m_ObjectHideFlags: 0