feat: implement user management system

- Add role field to UserProfile (superadmin/admin/trainer)
- Add role-based permission classes
- Create UserManagementViewSet with CRUD and password change
- Add API types and components for user management
- Create users management page in settings
- Only superadmins can manage users

frontend/next.config.ts

@@ -1,7 +1,10 @@
 import type { NextConfig } from "next";
 
 const nextConfig: NextConfig = {
-  /* config options here */
+  output: 'standalone',
+  images: {
+    unoptimized: true,
+  },
 };
 
 export default nextConfig;