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/notification/config-service.ts

@@ -1,4 +1,5 @@
 import path from 'node:path'
+import type { JsonObject } from '../../types/json.js'
 
 import { APP_CONFIG_KEYS } from '../../config/app-config-keys.js'
 import { PROJECT_ROOT } from '../../config/runtime.js'
@@ -10,7 +11,6 @@ import {
 const NOTIFICATION_CONFIG_FILE_PATH = path.join(PROJECT_ROOT, 'data', 'notification-config.json')
 const DEFAULT_BARK_SERVER_URL = 'https://api.day.app'
 
-type JsonObject = Record<string, any>
 type NotificationRecipient = {
   id: string
   name: string