Refactor AdminPage and remove AdminPanel component: Simplify admin navigation by redirecting to preferences page and eliminating the AdminPanel component, streamlining the admin interface.

components/admin/UserManagement.tsx

@@ -37,19 +37,19 @@ interface EditingUser {
   role: string | null;
 }
 
-export default function UserManagement() {
-  const [users, setUsers] = useState<User[]>([]);
-  const [loading, setLoading] = useState(true);
+interface UserManagementProps {
+  initialUsers: User[];
+}
+
+export default function UserManagement({ initialUsers }: UserManagementProps) {
+  const [users, setUsers] = useState<User[]>(initialUsers);
+  const [loading, setLoading] = useState(false);
   const [editingUser, setEditingUser] = useState<EditingUser | null>(null);
   const [saving, setSaving] = useState(false);
   const [deletingUserId, setDeletingUserId] = useState<string | null>(null);
   const [, startTransition] = useTransition();
   const [uploadingAvatar, setUploadingAvatar] = useState<string | null>(null);
 
-  useEffect(() => {
-    fetchUsers();
-  }, []);
-
   const fetchUsers = async () => {
     try {
       const response = await fetch("/api/admin/users");
@@ -59,8 +59,6 @@ export default function UserManagement() {
       }
     } catch (error) {
       console.error("Error fetching users:", error);
-    } finally {
-      setLoading(false);
     }
   };