收紧后端 TypeScript：统一 Json 类型与 TaskContext 契约

关闭 allowJs；集中 JsonObject 定义并替换分散 any 别名；parseTaskContext 返回 TaskContext；任务详情 API 标注 AdminTaskDetailView；测试减少 as any。

apps/backend/src/services/admin/admin-audit-service.ts

@@ -1,8 +1,7 @@
 import { createAdminAuditLog, listAdminAuditLogs } from '../../repositories/admin-audit-log-repo.js'
 import { nowIso } from '../../utils/time.js'
 import { normalizeDateQuery, normalizePage, normalizePageSize, safeParseJson } from './admin-query-utils.js'
-
-type JsonObject = Record<string, any>
+import type { JsonObject } from '../../types/json.js'
 
 export async function writeAdminAuditLog(session: JsonObject | null | undefined, payload: JsonObject = {}) {
   if (!session?.userId) {