refactor: 消除占位页面 + 删除 barrel 导出 — 页面集中注册 + 直接导入

- 删除 8 个占位页面文件（Account/Vip/Recharge/Billing/Orders/Projects/Quota/ComplianceAssets）
- PageDispatcher: PAGE_MAP 支持无组件页面自动渲染 PlaceholderPage
- 新增页面只需在 PAGE_MAP 加一行配置，无需创建独立文件
- 删除 services/modules/index.ts barrel，13 个文件改为直接导入
- IDE 跳转到定义一步到位，import 自文档化
- TypeScript 编译零错误

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/AppProvider.tsx

@@ -12,11 +12,10 @@ import type { Platform, Edition } from '@shared/types';
 
 import { getPlatform, isDev } from '@/utils/platform';
 import { safeIpcOn, safeIpcOff } from '@/utils/ipc';
-import type { LoginResponseBody } from '@/services/modules';
+import { AuthAPI, type LoginResponseBody } from '@/services/modules/auth';
 import { setToken, clearToken, initTokenStore } from '@/services/request';
 import { emit, EVENTS } from '@/utils/event-bus';
 import { logger } from '@/utils/logger';
-import { AuthAPI } from '@/services/modules';
 import { getAutoLoginFlag, clearAutoLoginFlag } from '@/services/auth-persistence';
 import {
    initAuthRefresh,