feat: 支付闭环 + 运营助手 Tool Calling + 管理后台完善

- 支付系统：微信支付 mock 自动完成、NATIVE 扫码支付、JSAPI 集成
- 运营助手：Tool Calling 架构，19 个可执行工具，AI 驱动操作
- 角色管理：表格布局 + Dialog 表单 + 权限勾选
- 配置统一：config.ts 单一数据源
- API 审计：补齐 status toggle / comments 端点
- 暗黑模式硬件编码颜色全部替换为 CSS 变量

backend/src/modules/admin/admin.module.ts

@@ -3,17 +3,19 @@ import { JwtModule } from '@nestjs/jwt';
 import { AdminController } from './admin.controller';
 import { AdminService } from './admin.service';
 import { AdminGuard } from './admin.guard';
+import { AdminAiAssistantService } from './ai-assistant.service';
 import { AnalyticsController } from './analytics.controller';
 import { SettingsController } from './settings.controller';
 import { OperationsController } from './operations.controller';
 import { UsersController } from './users.controller';
 import { CoursesModule } from '../courses/courses.module';
 import { AuthModule } from '../auth/auth.module';
+import { AIModule } from '../ai/ai.module';
 
 @Module({
-  imports: [CoursesModule, AuthModule],
+  imports: [CoursesModule, AuthModule, AIModule],
   controllers: [AdminController, AnalyticsController, SettingsController, OperationsController, UsersController],
-  providers: [AdminService, AdminGuard],
+  providers: [AdminService, AdminGuard, AdminAiAssistantService],
   exports: [AdminService],
 })
 export class AdminModule {}