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/admin/admin-payment-methods.service.d.ts

@@ -0,0 +1,78 @@
+import { PrismaService } from '../prisma/prisma.service';
+export declare class AdminPaymentMethodsService {
+    private readonly prisma;
+    constructor(prisma: PrismaService);
+    findAll(): Promise<{
+        id: string;
+        type: string;
+        provider: string;
+        accountName: string;
+        accountNumber: string;
+        displayName: string;
+        logoUrl: string | null;
+        instructions: string | null;
+        isActive: boolean;
+        sortOrder: number;
+        createdAt: Date;
+        updatedAt: Date;
+    }[]>;
+    findOne(id: string): Promise<{
+        id: string;
+        type: string;
+        provider: string;
+        accountName: string;
+        accountNumber: string;
+        displayName: string;
+        logoUrl: string | null;
+        instructions: string | null;
+        isActive: boolean;
+        sortOrder: number;
+        createdAt: Date;
+        updatedAt: Date;
+    } | null>;
+    create(data: any): Promise<{
+        id: string;
+        type: string;
+        provider: string;
+        accountName: string;
+        accountNumber: string;
+        displayName: string;
+        logoUrl: string | null;
+        instructions: string | null;
+        isActive: boolean;
+        sortOrder: number;
+        createdAt: Date;
+        updatedAt: Date;
+    }>;
+    update(id: string, data: any): Promise<{
+        id: string;
+        type: string;
+        provider: string;
+        accountName: string;
+        accountNumber: string;
+        displayName: string;
+        logoUrl: string | null;
+        instructions: string | null;
+        isActive: boolean;
+        sortOrder: number;
+        createdAt: Date;
+        updatedAt: Date;
+    }>;
+    delete(id: string): Promise<{
+        id: string;
+        type: string;
+        provider: string;
+        accountName: string;
+        accountNumber: string;
+        displayName: string;
+        logoUrl: string | null;
+        instructions: string | null;
+        isActive: boolean;
+        sortOrder: number;
+        createdAt: Date;
+        updatedAt: Date;
+    }>;
+    reorder(methodIds: string[]): Promise<{
+        success: boolean;
+    }>;
+}