add data service and homepage data retrieval

lib/components/login/login.dart

@@ -167,7 +167,11 @@ class _LoginPanelContentState extends State<LoginPanelContent> {
 }
 
 class RegisterPanelContent extends StatelessWidget {
-  const RegisterPanelContent({required this.onBack, required this.authService});
+  const RegisterPanelContent({
+    super.key,
+    required this.onBack,
+    required this.authService,
+  });
   final VoidCallback onBack;
   final AuthService authService;
   void register() {}