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/UserService.KVLoad.cs

@@ -1,8 +1,13 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Net;
+using System.Net.Http;
+using System.Threading;
 using System.Threading.Tasks;
+using asap.core;
 using game.PlayerDataStorage;
+using UnityEngine;
 
 namespace game
 {
@@ -105,6 +110,14 @@ namespace game
             EAccoutUrl=state.AccountUrls.ToDictionary(p=>p.Key,p=>p.Value,StringComparer.Ordinal);
             ReplaceKVLinked(state);
         }
+        void IKVUserLoadReceiver.ResetForKVLoad() => ResetForKVLoad();
+        void IKVUserLoadReceiver.ReplaceFromKVDecoded(PlayerKVLoginState state,long epoch,IReadOnlyDictionary<string,string> raw)
+            => ReplaceFromKVDecoded(state,epoch,raw);
+        void IKVUserLoadReceiver.DiscardKVIntents() => KVIntents?.Discard();
+        bool IKVUserLifecycle.KVHandoffReady => false;
+        PlayerKVGameLoadError IKVUserLifecycle.KVLastError => KVLastError;
+        Task IKVUserLifecycle.CloseKVForValidationAsync() => CloseKVForValidationAsync();
+        Task<PlayerKVShutdownStatus> IKVUserLifecycle.ObserveKVQuitAsync() => ObserveKVQuitAsync();
         internal virtual void ReplaceKVLinked(PlayerKVLoginState state) { }
     }
 }