feat: add SQLAlchemy models for Category, CategoryWord, Game, Word

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/conftest.py

@@ -0,0 +1,16 @@
+import pytest
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+from models import Base
+
+
+@pytest.fixture
+def db_session():
+    engine = create_engine("sqlite:///:memory:")
+    Base.metadata.create_all(engine)
+    Session = sessionmaker(bind=engine)
+    session = Session()
+    yield session
+    session.close()
+    engine.dispose()