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/start.py

@@ -9,14 +9,49 @@ from aiogram.types import (
     KeyboardButton,
 )
 from aiogram.fsm.context import FSMContext
+from aiogram.fsm.state import State, StatesGroup
 
 from database.db import async_session_maker
 from services.user_service import UserService
-from utils.i18n import t
+from utils.i18n import t, get_user_translation_lang
 from utils.levels import get_user_level_for_language
 
 router = Router()
 
+
+class OnboardingStates(StatesGroup):
+    """Состояния онбординга для новых пользователей"""
+    choosing_interface_lang = State()
+    choosing_learning_lang = State()
+    choosing_translation_lang = State()
+
+
+def onboarding_interface_keyboard() -> InlineKeyboardMarkup:
+    """Клавиатура выбора языка интерфейса при онбординге"""
+    return InlineKeyboardMarkup(inline_keyboard=[
+        [InlineKeyboardButton(text="🇷🇺 Русский", callback_data="onboard_interface_ru")],
+        [InlineKeyboardButton(text="🇬🇧 English", callback_data="onboard_interface_en")],
+        [InlineKeyboardButton(text="🇯🇵 日本語", callback_data="onboard_interface_ja")],
+    ])
+
+
+def onboarding_learning_keyboard(lang: str) -> InlineKeyboardMarkup:
+    """Клавиатура выбора языка изучения при онбординге"""
+    return InlineKeyboardMarkup(inline_keyboard=[
+        [InlineKeyboardButton(text=t(lang, 'onboarding.lang_en'), callback_data="onboard_learning_en")],
+        [InlineKeyboardButton(text=t(lang, 'onboarding.lang_ja'), callback_data="onboard_learning_ja")],
+    ])
+
+
+def onboarding_translation_keyboard(lang: str) -> InlineKeyboardMarkup:
+    """Клавиатура выбора языка перевода при онбординге"""
+    return InlineKeyboardMarkup(inline_keyboard=[
+        [InlineKeyboardButton(text=t(lang, 'settings.lang_name.ru'), callback_data="onboard_translation_ru")],
+        [InlineKeyboardButton(text=t(lang, 'settings.lang_name.en'), callback_data="onboard_translation_en")],
+        [InlineKeyboardButton(text=t(lang, 'settings.lang_name.ja'), callback_data="onboard_translation_ja")],
+    ])
+
+
 def main_menu_keyboard(lang: str = 'ru') -> ReplyKeyboardMarkup:
     """Клавиатура с основными командами (кнопки отправляют команды)."""
     return ReplyKeyboardMarkup(
@@ -46,35 +81,111 @@ async def cmd_start(message: Message, state: FSMContext):
         existing_user = await UserService.get_user_by_telegram_id(session, message.from_user.id)
         is_new_user = existing_user is None
 
-        # Создаём или получаем пользователя
-        user = await UserService.get_or_create_user(
-            session,
-            telegram_id=message.from_user.id,
-            username=message.from_user.username
-        )
+        if is_new_user:
+            # Новый пользователь - начинаем онбординг
+            # Сначала создаём пользователя с дефолтными значениями
+            user = await UserService.get_or_create_user(
+                session,
+                telegram_id=message.from_user.id,
+                username=message.from_user.username
+            )
 
+            # Приветствие и первый вопрос - язык интерфейса
+            await message.answer(
+                f"👋 Welcome! / Привет! / ようこそ!\n\n"
+                "🌐 Choose your interface language:\n"
+                "🌐 Выбери язык интерфейса:\n"
+                "🌐 インターフェース言語を選択:",
+                reply_markup=onboarding_interface_keyboard()
+            )
+            await state.set_state(OnboardingStates.choosing_interface_lang)
+            return
+
+        # Существующий пользователь
+        user = existing_user
         lang = (user.language_interface or 'ru')
 
-        if is_new_user:
-            # Новый пользователь
-            await message.answer(
-                t(lang, "start.new_intro", first_name=message.from_user.first_name),
-                reply_markup=main_menu_keyboard(lang),
-            )
+        await message.answer(
+            t(lang, "start.return", first_name=message.from_user.first_name),
+            reply_markup=main_menu_keyboard(lang),
+        )
 
-            # Предлагаем пройти тест уровня
-            keyboard = InlineKeyboardMarkup(inline_keyboard=[
-                [InlineKeyboardButton(text=t(lang, 'start.offer_btn'), callback_data="offer_level_test")],
-                [InlineKeyboardButton(text=t(lang, 'start.skip_btn'), callback_data="skip_level_test")]
-            ])
 
-            await message.answer(t(lang, "start.offer_test"), reply_markup=keyboard)
-        else:
-            # Существующий пользователь
-            await message.answer(
-                t(lang, "start.return", first_name=message.from_user.first_name),
-                reply_markup=main_menu_keyboard(lang),
-            )
+# === Обработчики онбординга ===
+
+@router.callback_query(F.data.startswith("onboard_interface_"), OnboardingStates.choosing_interface_lang)
+async def onboard_set_interface(callback: CallbackQuery, state: FSMContext):
+    """Установить язык интерфейса при онбординге"""
+    lang = callback.data.split("_")[-1]  # ru | en | ja
+
+    async with async_session_maker() as session:
+        user = await UserService.get_user_by_telegram_id(session, callback.from_user.id)
+        if user:
+            await UserService.update_user_language(session, user.id, lang)
+
+    await state.update_data(interface_lang=lang)
+
+    # Второй вопрос - язык изучения
+    await callback.message.edit_text(
+        t(lang, 'onboarding.step2_title'),
+        reply_markup=onboarding_learning_keyboard(lang)
+    )
+    await state.set_state(OnboardingStates.choosing_learning_lang)
+    await callback.answer()
+
+
+@router.callback_query(F.data.startswith("onboard_learning_"), OnboardingStates.choosing_learning_lang)
+async def onboard_set_learning(callback: CallbackQuery, state: FSMContext):
+    """Установить язык изучения при онбординге"""
+    learning_lang = callback.data.split("_")[-1]  # en | ja
+    data = await state.get_data()
+    lang = data.get('interface_lang', 'ru')
+
+    async with async_session_maker() as session:
+        user = await UserService.get_user_by_telegram_id(session, callback.from_user.id)
+        if user:
+            await UserService.update_user_learning_language(session, user.id, learning_lang)
+
+    await state.update_data(learning_lang=learning_lang)
+
+    # Третий вопрос - язык перевода
+    await callback.message.edit_text(
+        t(lang, 'onboarding.step3_title'),
+        reply_markup=onboarding_translation_keyboard(lang)
+    )
+    await state.set_state(OnboardingStates.choosing_translation_lang)
+    await callback.answer()
+
+
+@router.callback_query(F.data.startswith("onboard_translation_"), OnboardingStates.choosing_translation_lang)
+async def onboard_set_translation(callback: CallbackQuery, state: FSMContext):
+    """Установить язык перевода при онбординге и завершить"""
+    translation_lang = callback.data.split("_")[-1]  # ru | en | ja
+    data = await state.get_data()
+    lang = data.get('interface_lang', 'ru')
+
+    async with async_session_maker() as session:
+        user = await UserService.get_user_by_telegram_id(session, callback.from_user.id)
+        if user:
+            await UserService.update_user_translation_language(session, user.id, translation_lang)
+
+    await state.clear()
+
+    # Приветствие с выбранными настройками
+    await callback.message.edit_text(t(lang, 'onboarding.complete'))
+
+    # Показываем главное меню и предлагаем тест уровня
+    await callback.message.answer(
+        t(lang, "start.new_intro", first_name=callback.from_user.first_name),
+        reply_markup=main_menu_keyboard(lang),
+    )
+
+    keyboard = InlineKeyboardMarkup(inline_keyboard=[
+        [InlineKeyboardButton(text=t(lang, 'start.offer_btn'), callback_data="offer_level_test")],
+        [InlineKeyboardButton(text=t(lang, 'start.skip_btn'), callback_data="skip_level_test")]
+    ])
+    await callback.message.answer(t(lang, "start.offer_test"), reply_markup=keyboard)
+    await callback.answer()
 
 
 @router.message(Command("menu"))
@@ -329,7 +440,7 @@ async def pick_theme_from_menu(callback: CallbackQuery, state: FSMContext):
             level=current_level,
             count=10,
             learning_lang=user.learning_language,
-            translation_lang=user.language_interface,
+            translation_lang=get_user_translation_lang(user),
         )
         await generating.delete()
 
@@ -341,7 +452,7 @@ async def pick_theme_from_menu(callback: CallbackQuery, state: FSMContext):
         await state.update_data(theme=theme, words=words, user_id=user.id, level=current_level)
         await state.set_state(WordsStates.viewing_words)
 
-        await show_words_list(callback.message, words, theme)
+        await show_words_list(callback.message, words, theme, user.id)
 
 
 @router.message(Command("help"))
@@ -359,7 +470,7 @@ async def offer_level_test_callback(callback: CallbackQuery, state: FSMContext):
     """Начать тест уровня из приветствия"""
     from bot.handlers.level_test import start_level_test
     await callback.message.delete()
-    await start_level_test(callback.message, state)
+    await start_level_test(callback.message, state, telegram_id=callback.from_user.id)
     await callback.answer()