refactor(admin): 合并管理后台并移除 apps/agent

- 平台与代理共用 apps/admin，统一登录 manage/auth/login
- 按 userType 展示菜单，修复 token 循环跳转
- 删除独立 apps/agent 前端工程

Co-authored-by: Cursor <cursoragent@cursor.com>

apps/admin/package.json

@@ -2,6 +2,7 @@
   "name": "@thebet365/admin",
   "version": "1.0.0",
   "private": true,
+  "description": "统一管理后台（平台管理员 + 代理，单入口登录）",
   "type": "module",
   "scripts": {
     "dev": "vite --port 5174",