继续收紧 TypeScript：ClaimIdentity 契约与 flow 出口类型

- 新增 types/claim-identity，统一 ClaimIdentity / Payload / AdminSummary
- 导出 KuaishouCloudFlow、KuaishouFeifeiFlow 作为 normalize 出口
- 生产路径 JsonObject 统一从 types/json 导入，去掉 rebind as any
- 前后端 claimIdentity 类型字段对齐

apps/backend/src/utils/json.ts

@@ -1,9 +1,8 @@
+import type { JsonObject } from '../types/json.js'
 import { createHttpError } from './http.js'
 
 const LARGE_INTEGER_PATTERN = /(:\s*)(-?\d{16,})(\s*[,}\]])/g
 
-type JsonObject = Record<string, unknown>
-
 type ParseJsonObjectOptions = {
   preserveLargeIntegers?: boolean
   throwOnError?: boolean