add

app_core/db/database.py

@@ -0,0 +1,21 @@
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker, declarative_base
+from app_core.config.settings import AppSettings
+
+settings = AppSettings()
+
+if not settings.database_url:
+    raise RuntimeError(
+        "Database configuration missing. Set DATABASE_URL or DB_HOST/DB_PORT/DB_NAME/DB_USER/DB_PASSWORD in a .env file at the project root."
+    )
+
+engine = create_engine(settings.database_url, pool_pre_ping=True, future=True, echo=settings.db_echo)
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine, future=True)
+Base = declarative_base()
+
+def get_db_session():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()