no separate login/register page, use modal throughout

frontend/src/pages/ItemRequestDetail.tsx

@@ -4,6 +4,7 @@ import { useAuth } from '../contexts/AuthContext';
 import { itemRequestAPI } from '../services/api';
 import { ItemRequest, ItemRequestResponse } from '../types';
 import RequestResponseModal from '../components/RequestResponseModal';
+import AuthButton from '../components/AuthButton';
 
 const ItemRequestDetail: React.FC = () => {
   const { id } = useParams<{ id: string }>();
@@ -330,9 +331,9 @@ const ItemRequestDetail: React.FC = () => {
                   </div>
                 ) : !user ? (
                   <div className="text-center">
-                    <Link to="/login" className="btn btn-outline-primary">
+                    <AuthButton mode="login" className="btn btn-outline-primary">
                       Log in to Respond
-                    </Link>
+                    </AuthButton>
                   </div>
                 ) : null}