feat: complete admin backend controllers and services

- AdminPlansController & Service (CRUD, reorder)
- AdminPaymentMethodsController & Service (CRUD, reorder)
- AdminPaymentsController & Service (verify, reject, pending count)
- AdminUsersController & Service (search, suspend, grant pro access, stats)
- AdminConfigController & Service (dynamic config management)
- Wire all controllers into AdminModule
- Import AdminModule in AppModule

Admin API Routes:
- GET/POST/PUT/DELETE /admin/plans
- GET/POST/PUT/DELETE /admin/payment-methods
- GET /admin/payments (with status filter)
- POST /admin/payments/:id/verify
- POST /admin/payments/:id/reject
- GET /admin/users (with search)
- POST /admin/users/:id/grant-pro
- GET/POST/DELETE /admin/config

All routes protected by AuthGuard + AdminGuard

apps/api/dist/app.module.js

@@ -51,6 +51,7 @@ const wallets_module_1 = require("./wallets/wallets.module");
 const transactions_module_1 = require("./transactions/transactions.module");
 const categories_module_1 = require("./categories/categories.module");
 const otp_module_1 = require("./otp/otp.module");
+const admin_module_1 = require("./admin/admin.module");
 let AppModule = class AppModule {
 };
 exports.AppModule = AppModule;
@@ -71,6 +72,7 @@ exports.AppModule = AppModule = __decorate([
             transactions_module_1.TransactionsModule,
             categories_module_1.CategoriesModule,
             otp_module_1.OtpModule,
+            admin_module_1.AdminModule,
         ],
         controllers: [health_controller_1.HealthController],
         providers: [],