chore: autoclose how to play dialog after 3 seconds

lib/select_character/view/character_selection_page.dart

@@ -1,5 +1,7 @@
 // ignore_for_file: public_member_api_docs
 
+import 'dart:async';
+
 import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:pinball/l10n/l10n.dart';
@@ -47,10 +49,20 @@ class CharacterSelectionView extends StatelessWidget {
             TextButton(
               onPressed: () {
                 Navigator.of(context).pop();
+                late Timer timer;
                 showDialog<void>(
                   context: context,
-                  builder: (_) => const HowToPlayDialog(),
-                );
+                  builder: (context) {
+                    timer = Timer(const Duration(seconds: 3), () {
+                      Navigator.of(context).pop();
+                    });
+                    return const HowToPlayDialog();
+                  },
+                ).then((_) {
+                  if (timer.isActive) {
+                    timer.cancel();
+                  }
+                });
               },
               child: Text(l10n.start),
             ),

test/select_character/view/character_selection_page_test.dart

@@ -1,5 +1,7 @@
 // ignore_for_file: prefer_const_constructors
 
+import 'dart:async';
+
 import 'package:bloc_test/bloc_test.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -84,7 +86,8 @@ void main() {
           .called(1);
     });
 
-    testWidgets('displays how to play dialog when start is tapped',
+    testWidgets(
+      'displays how to play dialog for 3 seconds when start is tapped',
       (tester) async {
         await tester.pumpApp(
           CharacterSelectionView(),
@@ -93,9 +96,12 @@ void main() {
         await tester.ensureVisible(find.byType(TextButton));
         await tester.tap(find.byType(TextButton));
         await tester.pumpAndSettle();
-
         expect(find.byType(HowToPlayDialog), findsOneWidget);
-    });
+        await tester.pump(Duration(seconds: 3));
+        await tester.pumpAndSettle();
+        expect(find.byType(HowToPlayDialog), findsNothing);
+      },
+    );
   });
 
   testWidgets('CharacterImageButton renders correctly', (tester) async {