Refactor timeout calculations for repeater and login frames to ensure minimum message size is respected; remove obsolete widget test file.

test/widget_test.dart

@@ -1,12 +0,0 @@
-import 'package:flutter_test/flutter_test.dart';
-import 'package:meshcore_open/main.dart';
-
-void main() {
-  testWidgets('App loads successfully', (WidgetTester tester) async {
-    // Build our app and trigger a frame.
-    await tester.pumpWidget(const MeshCoreApp());
-
-    // Verify that the app title appears
-    expect(find.text('MeshCore Open'), findsOneWidget);
-  });
-}