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-C2d-final-modules.json

@@ -0,0 +1,15 @@
+{
+  "Success": true,
+  "Result": "{ pureResult = {\"success\":true,\"caseId\":\"M08-M23\",\"assertions\":28,\"scope\":\"M08-M23-only\",\"fullB220\":false,\"sharedContainerTouched\":false}, moduleResult = {\"success\":true,\"caseId\":\"B2-20\",\"assertions\":83,\"errorType\":null,\"restored\":true,\"auth\":2,\"gets\":2,\"borrowed\":1,\"forbidden\":0,\"eventPublishes\":0,\"eventSubscriptions\":0,\"realModules\":31,\"sameObjects\":true,\"fullB220\":true,\"scope\":\"31-real-modules-two-epochs-controlled-transaction\"}, playing = False }",
+  "Logs": [
+    "Execution completed successfully",
+    "Performance hint: Auto-resolved 1 missing using directive(s): using UnityEngine.Rendering.VirtualTexturing; — Include them in your code to skip auto-resolution and improve compilation speed."
+  ],
+  "CompilationErrors": [],
+  "ErrorMessage": "",
+  "SecurityLevel": "Restricted",
+  "Error": "",
+  "UpdatedCode": null,
+  "DiagnosticsSummary": null,
+  "Diagnostics": []
+}