fix(flutter): 精简个人资料并修正保存文案

test/account/account_pages_test.dart

@@ -28,15 +28,19 @@ void main() {
       AccountProfilePage(),
       repository: repository,
       auth: auth,
+      locale: const Locale('zh'),
     );
 
     final nickname = find.byKey(const Key('account-nickname'));
+    expect(find.byKey(const Key('account-birthday')), findsNothing);
+    expect(find.text('保存'), findsOneWidget);
     expect(tester.widget<TextField>(nickname).controller?.text, 'Nadia');
     await tester.enterText(nickname, 'Nadia Baru');
     await tester.tap(find.byKey(const Key('account-profile-save')));
     await tester.pumpAndSettle();
 
     expect(repository.lastUpdate?.nickname, 'Nadia Baru');
+    expect(repository.lastUpdate?.birthday, isNull);
   });
 
   testWidgets('should_show_device_empty_state_when_list_is_empty', (