feat(app): show and write a word's senses with their grammar

A word with senses (as a dictionary gives them) shows them when its
answer shows: numbered when there are several, each with its label, its
translations and its grammar codes, small and slanted, their meaning on
hover. A word usually written in kana shows its reading from the start:
its kanji are rarely seen, so there is nothing to hide. The composer
writes the senses' translations, adds and removes senses, and keeps the
codes as they came.

The codes' short forms and meanings are the dictionary's own English
(JMdict's entities), kept as data beside the cards.

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

@@ -208,6 +208,41 @@ void main() {
     expect(saved.explanation, isNull);
   });
 
+  testWidgets("a word's senses are written as such, their grammar kept, its "
+      'meanings taken from them', (tester) async {
+    await cards.create(
+      'japanese',
+      CardContent(
+        type: CardType.vocabulary,
+        front: paragraph('食べる'),
+        back: RichContent.empty(),
+        meanings: const ['to eat', 'to live on'],
+        senses: const [
+          VocabularySense(glosses: ['to eat'], pos: ['v1']),
+          VocabularySense(glosses: ['to live on']),
+        ],
+      ),
+    );
+    await showStudyset(tester);
+    await open(tester, '食べる');
+    expect(find.text('Ichidan'), findsOneWidget);
+
+    await tester.tap(find.byTooltip('Remove sense').first);
+    await settle(tester);
+    await tester.enterText(
+      find.widgetWithText(TextField, 'to live on'),
+      'to make a living',
+    );
+    await tester.tap(find.text('New flashcard'));
+    await settle(tester);
+
+    final saved = (await cards.cardsOf('japanese')).first.content;
+    expect(saved.senses, const [
+      VocabularySense(glosses: ['to make a living']),
+    ]);
+    expect(saved.meanings, ['to make a living']);
+  });
+
   testWidgets('New flashcard opens the new card, also while the changed one '
       'it leaves is being saved', (tester) async {
     await cards.create('japanese', card('猫', 'cat'));