chore(m2): 保存功能验收及后续清理前检查点

Client/Assets/Scripts/Services/PlayerData/PlayerKVModels.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 
@@ -15,16 +16,23 @@ namespace game.PlayerDataStorage
         public int? StatusCode { get; }
         // Only a successful Get has Data. Failure must never look like an empty save.
         public IReadOnlyDictionary<string, string> Data { get; }
+        // Null means the response did not supply timestamp metadata; never substitute read time.
+        public IReadOnlyDictionary<string, DateTime> UpdatedAtUtc
+        {
+            get;
+        }
         // A failed write that entered the transport may already have reached the server.
         // This is conservative, including HTTP failures. Do not blindly replay the write.
         public bool MayHaveCommitted { get; }
 
         internal PlayerKVResult(PlayerKVError error, int? statusCode = null,
-            Dictionary<string, string> data = null, bool mayHaveCommitted = false)
+            Dictionary<string, string> data = null, bool mayHaveCommitted = false,
+            Dictionary<string, DateTime> updatedAtUtc = null)
         {
             Error = error;
             StatusCode = statusCode;
             Data = data == null ? null : new ReadOnlyDictionary<string, string>(data);
+            UpdatedAtUtc = updatedAtUtc == null ? null : new ReadOnlyDictionary<string, DateTime>(updatedAtUtc);
             MayHaveCommitted = mayHaveCommitted;
         }
     }