feat(upserver): 保存M2客户端KV迁移至本人统计写检查点

保存独立KV用户服务、固定会话存档与原业务接线，以及C3d资料缓存和C3e本人统计写。
保留原PF/AGG路线、业务公式和时序；榜单读取、好友资料、公告、匹配及首场景闸仍待完成。

验证：ServiceHost两条件各33组646断言；Unity CLI Loop编译0错误269警告。
包含相关方案、评审裁决、测试及状态文档。未操作服务器、正式账号或打包。

Client/Assets/Scripts/Services/DeferredRewardStashService.cs

@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using asap.core;
 using cfg;
 using game;
@@ -20,6 +20,8 @@ public interface IDeferredRewardStashService
 
 public class DeferredRewardStashService : IDeferredRewardStashService
 {
+    readonly game.PlayerDataStorage.IPlayerSaveStore saveStore = GContext.container.Resolve<game.PlayerDataStorage.IPlayerSaveStore>();
+
     private readonly TbItem _itemTable = GContext.container.Resolve<Tables>().TbItem;
     private readonly PlayerItemData _playerItemData = GContext.container.Resolve<PlayerItemData>();
     private CompositeDisposable _disposables;
@@ -190,13 +192,13 @@ public class DeferredRewardStashService : IDeferredRewardStashService
     public void UploadData()
     {
         var s = Serialize();
-        PlayFabMgr.Instance.UpdateUserDataValue(Key, s);
+        saveStore.Write(Key, s).RequireAccepted();
     }
 
     public void LoadData()
     {
+        var s = saveStore.Read(Key).ValueOrThrow();
         Reset();
-        var s = PlayFabMgr.Instance.GetLocalData(Key);
         if (string.IsNullOrEmpty(s))
             return;
         _items = Deserialize(s);