feat: add translation language setting & onboarding flow

- Add separate translation_language setting (independent from interface language)
- Implement 3-step onboarding for new users:
  1. Choose interface language
  2. Choose learning language
  3. Choose translation language
- Fix localization issues when using callback.message (user_id from state)
- Add UserService.get_user_by_id() method
- Add get_user_translation_lang() helper in i18n
- Update all handlers to use correct translation language
- Add localization keys for onboarding (ru/en/ja)

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

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

bot/handlers/words.py

@@ -9,7 +9,7 @@ from database.models import WordSource
 from services.user_service import UserService
 from services.vocabulary_service import VocabularyService
 from services.ai_service import ai_service
-from utils.i18n import t
+from utils.i18n import t, get_user_lang, get_user_translation_lang
 from utils.levels import get_user_level_for_language
 
 router = Router()
@@ -64,7 +64,7 @@ async def generate_words_for_theme(message: Message, state: FSMContext, theme: s
             level=current_level,
             count=10,
             learning_lang=user.learning_language,
-            translation_lang=user.language_interface,
+            translation_lang=get_user_translation_lang(user),
         )
 
         await generating_msg.delete()
@@ -83,15 +83,15 @@ async def generate_words_for_theme(message: Message, state: FSMContext, theme: s
         await state.set_state(WordsStates.viewing_words)
 
         # Показываем подборку
-        await show_words_list(message, words, theme)
+        await show_words_list(message, words, theme, user_id)
 
 
-async def show_words_list(message: Message, words: list, theme: str):
+async def show_words_list(message: Message, words: list, theme: str, user_id: int):
     """Показать список слов с кнопками для добавления"""
 
     # Определяем язык интерфейса для заголовка/подсказок
     async with async_session_maker() as session:
-        user = await UserService.get_user_by_telegram_id(session, message.from_user.id)
+        user = await UserService.get_user_by_telegram_id(session, user_id)
     lang = (user.language_interface if user else 'ru') or 'ru'
 
     text = t(lang, 'words.header', theme=theme) + "\n\n"
@@ -171,9 +171,9 @@ async def add_single_word(callback: CallbackQuery, state: FSMContext):
         # Добавляем слово
         # Формируем examples с учётом языков
         learn = user.learning_language if user else 'en'
-        ui = user.language_interface if user else 'ru'
+        translation_lang = get_user_translation_lang(user)
         ex = word_data.get('example')
-        examples = ([{learn: ex, ui: ''}] if ex else [])
+        examples = ([{learn: ex, translation_lang: ''}] if ex else [])
 
         await VocabularyService.add_word(
             session=session,
@@ -181,7 +181,7 @@ async def add_single_word(callback: CallbackQuery, state: FSMContext):
             word_original=word_data['word'],
             word_translation=word_data['translation'],
             source_lang=user.learning_language if user else None,
-            translation_lang=user.language_interface if user else None,
+            translation_lang=translation_lang,
             transcription=word_data.get('transcription'),
             examples=examples,
             source=WordSource.SUGGESTED,
@@ -222,9 +222,9 @@ async def add_all_words(callback: CallbackQuery, state: FSMContext):
 
             # Добавляем слово
             learn = user.learning_language if user else 'en'
-            ui = user.language_interface if user else 'ru'
+            translation_lang = get_user_translation_lang(user)
             ex = word_data.get('example')
-            examples = ([{learn: ex, ui: ''}] if ex else [])
+            examples = ([{learn: ex, translation_lang: ''}] if ex else [])
 
             await VocabularyService.add_word(
                 session=session,
@@ -232,7 +232,7 @@ async def add_all_words(callback: CallbackQuery, state: FSMContext):
                 word_original=word_data['word'],
                 word_translation=word_data['translation'],
                 source_lang=user.learning_language if user else None,
-                translation_lang=user.language_interface if user else None,
+                translation_lang=translation_lang,
                 transcription=word_data.get('transcription'),
                 examples=examples,
                 source=WordSource.SUGGESTED,
@@ -241,9 +241,10 @@ async def add_all_words(callback: CallbackQuery, state: FSMContext):
             )
             added_count += 1
 
-    result_text = f"✅ Добавлено слов: <b>{added_count}</b>"
+    lang = (user.language_interface if user else 'ru') or 'ru'
+    result_text = t(lang, 'import.added_count', n=added_count)
     if skipped_count > 0:
-        result_text += f"\n⚠️ Пропущено (уже в словаре): {skipped_count}"
+        result_text += "\n" + t(lang, 'import.skipped_count', n=skipped_count)
 
     await callback.message.edit_reply_markup(reply_markup=None)
     await callback.message.answer(result_text)