feat: restructure menu and add file import

- Consolidate "Add word" menu with submenu (Manual, Thematic, Import)
- Add file import support (.txt, .md) with AI batch translation
- Add vocabulary pagination with navigation buttons
- Add "Add word" button in tasks for new words mode
- Fix undefined variables bug in vocabulary confirm handler
- Add localization keys for add_menu in ru/en/ja

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

services/vocabulary_service.py

@@ -90,14 +90,21 @@ class VocabularyService:
         return [w for w in words if not VocabularyService._is_japanese(w.word_original)]
 
     @staticmethod
-    async def get_user_words(session: AsyncSession, user_id: int, limit: int = 50, learning_lang: Optional[str] = None) -> List[Vocabulary]:
+    async def get_user_words(
+        session: AsyncSession,
+        user_id: int,
+        limit: int = 50,
+        offset: int = 0,
+        learning_lang: Optional[str] = None
+    ) -> List[Vocabulary]:
         """
-        Получить все слова пользователя
+        Получить слова пользователя с пагинацией
 
         Args:
             session: Сессия базы данных
             user_id: ID пользователя
             limit: Максимальное количество слов
+            offset: Смещение для пагинации
 
         Returns:
             Список слов пользователя
@@ -109,7 +116,7 @@ class VocabularyService:
         )
         words = list(result.scalars().all())
         words = VocabularyService._filter_by_learning_lang(words, learning_lang)
-        return words[:limit]
+        return words[offset:offset + limit]
 
     @staticmethod
     async def get_words_count(session: AsyncSession, user_id: int, learning_lang: Optional[str] = None) -> int: