Restructure into full project layout

backend/app/core/database.py

@@ -0,0 +1,16 @@
+from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker, AsyncSession
+from sqlalchemy.orm import DeclarativeBase
+
+from app.core.config import settings
+
+engine = create_async_engine(settings.DATABASE_URL, echo=False)
+AsyncSessionLocal = async_sessionmaker(engine, expire_on_commit=False)
+
+
+class Base(DeclarativeBase):
+    pass
+
+
+async def get_db() -> AsyncSession:
+    async with AsyncSessionLocal() as session:
+        yield session