ADD: added raw structure

frontend/src/App.tsx

@@ -0,0 +1,12 @@
+import React from 'react';
+import GroupsPage from './pages/GroupsPage';
+
+function App() {
+  return (
+    <div className="min-h-screen bg-gray-100">
+      <GroupsPage />
+    </div>
+  );
+}
+
+export default App;