refactor: 将淡入淡出迁移到 ScreenTransitionPanel

- 将 BaseYarnCommand、FixSystemNew 各状态、GameManager、
  SaveSystem、PlayToolPanel 中的 PlayToolPanel 遮罩调用
  统一迁移到 ScreenTransitionPanel
- 从 PlayToolPanel 移除 _fadeImage 及相关 fade 方法
- 从 Play Tool Panel Prefab 移除 Fade Image 子对象

Assets/Scripts/SaveSystem/ScreenSnapshotHelper.cs

@@ -4,8 +4,8 @@ using UnityEngine;
 namespace AibisDream.SaveSystem
 {
     /// <summary>
-    /// screen section 的捕获/还原实现：屏幕后处理饱和度 + PlayToolPanel 遮罩终态（黑屏盖住 / 画面可见）。
-    /// screen section：饱和度 + PlayToolPanel 遮罩终态（<see cref="PlayToolPanel.CaptureFadeScreenCovered"/>）。
+    /// screen section 的捕获/还原实现：屏幕后处理饱和度 + ScreenTransitionPanel 遮罩终态。
+    /// screen section：饱和度 + 全局遮罩终态（<see cref="ScreenTransitionPanel.CaptureScreenCovered"/>）。
     /// 供 <see cref="ScreenSnapshotProvider"/> 委托，避免 Provider 直接依赖 UI 细节。
     /// </summary>
     public static class ScreenSnapshotHelper
@@ -24,10 +24,10 @@ namespace AibisDream.SaveSystem
 
             if (UIManager.Instance != null)
             {
-                var panel = UIManager.Instance.GetPanel<PlayToolPanel>();
+                var panel = UIManager.Instance.GetPanel<ScreenTransitionPanel>();
                 if (panel != null)
                 {
-                    dto.isFadeScreenCovered = panel.CaptureFadeScreenCovered();
+                    dto.isFadeScreenCovered = panel.CaptureScreenCovered();
                 }
             }
 
@@ -52,8 +52,8 @@ namespace AibisDream.SaveSystem
                     return;
                 }
 
-                var panel = UIManager.Instance.GetPanel<PlayToolPanel>();
-                panel?.ApplyFadeScreenCovered(dto.isFadeScreenCovered);
+                var panel = UIManager.Instance.GetPanel<ScreenTransitionPanel>();
+                panel?.ApplyScreenCovered(dto.isFadeScreenCovered);
             }
         }
 
@@ -66,8 +66,8 @@ namespace AibisDream.SaveSystem
             }
 
             _hasDeferredFadeScreenCovered = false;
-            var panel = UIManager.Instance?.GetPanel<PlayToolPanel>();
-            panel?.ApplyFadeScreenCovered(_deferredFadeScreenCovered);
+            var panel = UIManager.Instance?.GetPanel<ScreenTransitionPanel>();
+            panel?.ApplyScreenCovered(_deferredFadeScreenCovered);
         }
     }
 }