Refactor and centralize user and pagination interfaces in useAdmin hook

- Unified `User` and `PaginationMeta` type definitions into `useAdmin` to improve maintainability and consistency.
- Updated affected components (`UserManagementContent`, `UserListTable`, `UserFormDialog`, `UserActionMenu`) to reference the centralized types.
- Enhanced test coverage for user-related hooks to include create, update, delete, activate, deactivate, and bulk actions.

frontend/src/components/admin/users/UserActionMenu.tsx

@@ -30,17 +30,9 @@ import {
   useActivateUser,
   useDeactivateUser,
   useDeleteUser,
+  type User,
 } from '@/lib/api/hooks/useAdmin';
 
-interface User {
-  id: string;
-  email: string;
-  first_name: string;
-  last_name: string | null;
-  is_active: boolean;
-  is_superuser: boolean;
-}
-
 interface UserActionMenuProps {
   user: User;
   isCurrentUser: boolean;

frontend/src/components/admin/users/UserFormDialog.tsx

@@ -26,6 +26,7 @@ import { toast } from 'sonner';
 import {
   useCreateUser,
   useUpdateUser,
+  type User,
 } from '@/lib/api/hooks/useAdmin';
 
 // ============================================================================
@@ -58,15 +59,6 @@ type UserFormData = z.infer<typeof userFormSchema>;
 // Component
 // ============================================================================
 
-interface User {
-  id: string;
-  email: string;
-  first_name: string;
-  last_name: string | null;
-  is_active: boolean;
-  is_superuser: boolean;
-}
-
 interface UserFormDialogProps {
   open: boolean;
   onOpenChange: (open: boolean) => void;

frontend/src/components/admin/users/UserListTable.tsx

@@ -29,25 +29,7 @@ import {
   SelectValue,
 } from '@/components/ui/select';
 import { UserActionMenu } from './UserActionMenu';
-
-interface User {
-  id: string;
-  email: string;
-  first_name: string;
-  last_name: string | null;
-  is_active: boolean;
-  is_superuser: boolean;
-  created_at: string;
-}
-
-interface PaginationMeta {
-  total: number;
-  page: number;
-  page_size: number;
-  total_pages: number;
-  has_next: boolean;
-  has_prev: boolean;
-}
+import type { User, PaginationMeta } from '@/lib/api/hooks/useAdmin';
 
 interface UserListTableProps {
   users: User[];

frontend/src/components/admin/users/UserManagementContent.tsx

@@ -10,7 +10,7 @@ import { useSearchParams, useRouter } from 'next/navigation';
 import { Plus } from 'lucide-react';
 import { Button } from '@/components/ui/button';
 import { useAuth } from '@/lib/auth/AuthContext';
-import { useAdminUsers } from '@/lib/api/hooks/useAdmin';
+import { useAdminUsers, type User, type PaginationMeta } from '@/lib/api/hooks/useAdmin';
 import { UserListTable } from './UserListTable';
 import { UserFormDialog } from './UserFormDialog';
 import { BulkActionToolbar } from './BulkActionToolbar';
@@ -30,13 +30,13 @@ export function UserManagementContent() {
   const [selectedUsers, setSelectedUsers] = useState<string[]>([]);
   const [dialogOpen, setDialogOpen] = useState(false);
   const [dialogMode, setDialogMode] = useState<'create' | 'edit'>('create');
-  const [editingUser, setEditingUser] = useState<any | null>(null);
+  const [editingUser, setEditingUser] = useState<User | null>(null);
 
   // Fetch users with query params
   const { data, isLoading } = useAdminUsers(page, 20);
 
-  const users = data?.data || [];
-  const pagination = data?.pagination || {
+  const users: User[] = data?.data || [];
+  const pagination: PaginationMeta = data?.pagination || {
     total: 0,
     page: 1,
     page_size: 20,
@@ -107,7 +107,7 @@ export function UserManagementContent() {
     setDialogOpen(true);
   };
 
-  const handleEditUser = (user: any) => {
+  const handleEditUser = (user: User) => {
     setDialogMode('edit');
     setEditingUser(user);
     setDialogOpen(true);