quite a few UX improvements

frontend/lib/structs/agreement.dart

@@ -0,0 +1,17 @@
+import 'package:shared_preferences/shared_preferences.dart';
+
+final class Agreement{
+  bool agreed;
+
+  Agreement({required this.agreed});
+}
+
+void saveAgreement(bool agreed) async {
+  SharedPreferences prefs = await SharedPreferences.getInstance();
+  prefs.setBool('agreed_to_terms_and_conditions', agreed);
+}
+
+Future<Agreement> getAgreement() async {
+  SharedPreferences prefs = await SharedPreferences.getInstance();
+  return Agreement(agreed: prefs.getBool('agreed_to_terms_and_conditions') ?? false);
+}