chore: remove the greetings demo

Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/test/widget_test.dart

@@ -1,15 +1,10 @@
-// This is a basic Flutter widget test.
-//
-// To perform an interaction with a widget in your test, use the WidgetTester
-// utility that Flutter provides. For example, you can send tap and scroll
-// gestures. You can also use WidgetTester to find child widgets in the widget
-// tree, read text, and verify that the values of widget properties are correct.
-
-// import 'package:flutter/material.dart';
-// import 'package:flutter_test/flutter_test.dart';
-//
-// import 'package:PROJECTNAME_flutter/main.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:halkyon_learn_flutter/main.dart';
 
 void main() {
-  // Add your app tests here
+  testWidgets('shows the app name', (tester) async {
+    await tester.pumpWidget(const HalkyonLearnApp());
+
+    expect(find.text('Halkyon Learn'), findsOneWidget);
+  });
 }