Python-code moved to backend/ directory.

backend/app/db.py

@@ -0,0 +1,9 @@
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker, DeclarativeBase
+from app.config import settings
+
+engine = create_engine(settings.database_url, future=True)
+SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False)
+
+class Base(DeclarativeBase):
+    pass