add new vocabulary mode

lib/src/models/kanji_item.dart

@@ -79,3 +79,61 @@ String _katakanaToHiragana(String input) {
   }
   return buf.toString();
 }
+
+enum VocabQuizMode { vocabToEnglish, englishToVocab }
+
+class VocabSrsItem {
+  final int vocabId;
+  final VocabQuizMode quizMode;
+  int srsStage;
+  DateTime lastAsked;
+
+  VocabSrsItem({
+    required this.vocabId,
+    required this.quizMode,
+    this.srsStage = 0,
+    DateTime? lastAsked,
+  }) : lastAsked = lastAsked ?? DateTime.now();
+}
+
+class VocabularyItem {
+  final int id;
+  final String characters;
+  final List<String> meanings;
+  final List<String> readings;
+  final Map<String, VocabSrsItem> srsItems = {};
+
+  VocabularyItem({
+    required this.id,
+    required this.characters,
+    required this.meanings,
+    required this.readings,
+  });
+
+  factory VocabularyItem.fromSubject(Map<String, dynamic> subj) {
+    final int id = subj['id'] as int;
+    final data = subj['data'] as Map<String, dynamic>;
+    final String characters = (data['characters'] ?? '') as String;
+    final List<String> meanings = <String>[];
+    final List<String> readings = <String>[];
+
+    if (data['meanings'] != null) {
+      for (final m in data['meanings'] as List) {
+        meanings.add((m['meaning'] as String).toLowerCase());
+      }
+    }
+
+    if (data['readings'] != null) {
+      for (final r in data['readings'] as List) {
+        readings.add(r['reading'] as String);
+      }
+    }
+
+    return VocabularyItem(
+      id: id,
+      characters: characters,
+      meanings: meanings,
+      readings: readings,
+    );
+  }
+}