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-等级榜设计范围纠正hash.json

@@ -0,0 +1,25 @@
+{
+  "date": "2026-09-30T17:06:10.5200080+08:00",
+  "scope": "LevelB scope correction: existing logic retained, new design only for leaderboard read endpoint",
+  "items": [
+    {
+      "path": "CodexOutput/upserver/B3BatchMigration/M2/M2-等级榜设计范围纠正-LevelB沿用原逻辑-2026-09-30.md",
+      "bytes": 2715,
+      "sha256": "62534980BD6F13AE91B873A68D5AE57D1E7AAB73F17412F2A2D624314F584DB6"
+    },
+    {
+      "path": "CodexOutput/upserver/B3BatchMigration/M2/M2-等级榜接口设计受审hash.json",
+      "bytes": 2649,
+      "sha256": "FFA8E3415E3383A65586F29C040C7CD9489387A4611ED24EEE7A912EF6C2EBB7"
+    },
+    {
+      "path": "Client/Assets/Scripts/DataCenter/DataCenter.LeadboardData.cs",
+      "bytes": 18731,
+      "sha256": "0A3F56F258C245196CA2609C62CFEBB97419993E45946CE69474CC819E1C9F2D"
+    }
+  ],
+  "previousBaselineMatched": 9,
+  "productionChanged": false,
+  "serverChanged": false,
+  "formalRequests": 0
+}