feat(i18n): localize start/help/menu, practice, words, import, reminder, vocabulary, tasks/stats for RU/EN/JA; add JSON-based i18n helper\n\nfeat(lang): support learning/translation languages across AI flows; hide translations with buttons; store examples per lang\n\nfeat(vocab): add source_lang and translation_lang to Vocabulary, unique constraint (user_id, source_lang, word_original); filter /vocabulary by user.learning_language\n\nchore(migrations): add Alembic setup + migration to add vocab lang columns; env.py reads app settings and supports asyncpg URLs\n\nfix(words/import): pass learning_lang + translation_lang everywhere; fix menu themes generation\n\nfeat(settings): add learning language selector; update main menu on language change

migrations/env.py

@@ -0,0 +1,93 @@
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+from sqlalchemy.ext.asyncio import create_async_engine
+from logging.config import fileConfig
+import sys, os
+
+# Ensure project root is on sys.path for importing config.settings
+PROJECT_ROOT = os.path.dirname(os.path.dirname(__file__))
+if PROJECT_ROOT not in sys.path:
+    sys.path.append(PROJECT_ROOT)
+
+try:
+    from config.settings import settings
+except Exception:
+    settings = None
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+target_metadata = None  # not used, explicit migrations only
+
+
+def _get_urls():
+    """Derive a sync SQLAlchemy URL from app settings (async -> sync)."""
+    async_url = None
+    sync_url = None
+    if settings and getattr(settings, 'database_url', None):
+        async_url = settings.database_url
+        sync_url = async_url
+        if async_url.startswith("postgresql+asyncpg://"):
+            sync_url = async_url.replace("postgresql+asyncpg://", "postgresql://", 1)
+    return async_url, sync_url
+
+
+def run_migrations_offline():
+    async_url, sync_url = _get_urls()
+    url = sync_url or config.get_main_option("sqlalchemy.url")
+    if url:
+        config.set_main_option("sqlalchemy.url", url)
+    context.configure(
+        url=url,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online():
+    async_url, sync_url = _get_urls()
+    # If we have an async URL, run migrations via async engine
+    if async_url and async_url.startswith("postgresql+asyncpg://"):
+        async def do_run_migrations():
+            connectable = create_async_engine(async_url, poolclass=pool.NullPool)
+            async with connectable.connect() as connection:
+                def sync_migrations(conn):
+                    context.configure(connection=conn)
+                    with context.begin_transaction():
+                        context.run_migrations()
+
+                await connection.run_sync(sync_migrations)
+
+        import asyncio
+        asyncio.run(do_run_migrations())
+        return
+
+    # Fallback to sync engine (e.g., if sync URL is provided)
+    url = sync_url or config.get_main_option("sqlalchemy.url")
+    if url:
+        config.set_main_option("sqlalchemy.url", url)
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(connection=connection)
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

migrations/versions/20251204_add_vocab_lang_fields.py

@@ -0,0 +1,30 @@
+"""add source_lang and translation_lang to vocabulary
+
+Revision ID: 20251204_add_vocab_lang
+Revises: 
+Create Date: 2025-12-04
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '20251204_add_vocab_lang'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.add_column('vocabulary', sa.Column('source_lang', sa.String(length=5), nullable=True))
+    op.add_column('vocabulary', sa.Column('translation_lang', sa.String(length=5), nullable=True))
+    # Create unique constraint for (user_id, source_lang, word_original)
+    op.create_unique_constraint('uq_vocab_user_lang_word', 'vocabulary', ['user_id', 'source_lang', 'word_original'])
+
+
+def downgrade():
+    op.drop_constraint('uq_vocab_user_lang_word', 'vocabulary', type_='unique')
+    op.drop_column('vocabulary', 'translation_lang')
+    op.drop_column('vocabulary', 'source_lang')
+