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。

CodexOutput/upserver/B3BatchMigration/M2/M2-C3c好友列表线上只读探测-final-2026-09-30.json

@@ -0,0 +1,39 @@
+{
+  "time": "2026-09-30T15:09:11.1993747+08:00",
+  "api": "http://s101.local:18080/",
+  "scope": "Existing 101/102 login and friend/GetFriendsList only; no KV Set/Delete, no profile payload or friend mutations; credentials and profile values omitted",
+  "records": [
+    {
+      "account": "101",
+      "loginHttp": 200,
+      "loginState": 0,
+      "newCreate": false,
+      "friendHttp": 200,
+      "friendCode": 1,
+      "responseFields": [
+        "code",
+        "msg",
+        "friends"
+      ],
+      "friendCount": 0,
+      "itemSchemas": [],
+      "error": null
+    },
+    {
+      "account": "102",
+      "loginHttp": 200,
+      "loginState": 0,
+      "newCreate": false,
+      "friendHttp": 200,
+      "friendCode": 1,
+      "responseFields": [
+        "code",
+        "msg",
+        "friends"
+      ],
+      "friendCount": 0,
+      "itemSchemas": [],
+      "error": null
+    }
+  ]
+}