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-合批-C2b自验汇总.json

@@ -0,0 +1,26 @@
+{
+  "date": "2026-09-29T21:25:00.038225+08:00",
+  "combinedHashEntriesVerified": 2177,
+  "checkpointHashEntriesVerified": 47,
+  "originalReviewAndManifestUnchanged": true,
+  "outsideCodeWhitelist": [],
+  "diffCheck": 0,
+  "unityEditor": {
+    "success": true,
+    "errors": 0,
+    "warnings": 272
+  },
+  "serviceHost": {
+    "nonAndroidGroups": 17,
+    "nonAndroidAssertions": 235,
+    "androidAggGroups": 17,
+    "androidAggAssertions": 235,
+    "formalRequests": 0
+  },
+  "gameLoadRerun": false,
+  "migratedBusinessCalls": 64,
+  "totalBusinessCalls": 202,
+  "productionCallRuntimeVerified": false,
+  "playOrPackaging": false,
+  "executionNote": "File.Replace/Node spawn blocked in sandbox; approved escalated local synthetic tests and CLI Loop compile passed"
+}