feat(app): card types on one row, scrolling sideways

On a phone the four chips wrapped onto a second row; they now stay on
one and scroll.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/test/feature/card/widget/card_composer_test.dart

@@ -393,21 +393,31 @@ void main() {
     expect(blocks, contains(containsPair('type', mathBlockType)));
   });
 
-  testWidgets('the card types fit a phone, none of their names broken', (
-    tester,
-  ) async {
+  testWidgets('the card types stay on one row on a phone, scrolling '
+      'sideways, none of their names broken', (tester) async {
     await cards.create('japanese', card('猫', 'cat'));
     await showStudyset(tester, size: const Size(412, 915));
     await open(tester, '猫');
 
-    for (final type in ['Flashcard', 'Vocabulary', 'Matching', 'Map']) {
+    const types = ['Flashcard', 'Vocabulary', 'Matching', 'Map'];
+    for (final type in types) {
       final name = tester.renderObject<RenderParagraph>(find.text(type));
       expect(
         name.size.width,
         moreOrLessEquals(name.getMaxIntrinsicWidth(double.infinity)),
         reason: type,
       );
+      expect(
+        tester.getCenter(find.text(type)).dy,
+        tester.getCenter(find.text(types.first)).dy,
+        reason: type,
+      );
     }
+    await tester.ensureVisible(find.text('Map'));
+    await tester.pumpAndSettle();
+    expect(find.text('Map').hitTestable(), findsOneWidget);
+    await tester.ensureVisible(find.text('Vocabulary'));
+    await tester.pumpAndSettle();
     await tester.tap(find.text('Vocabulary'));
     await settle(tester);
     expect(find.text('Reading'), findsOneWidget);