feat: implement backend knowledge management

backend/app/db/session.py

@@ -1,16 +1,25 @@
 from sqlalchemy import create_engine
 from sqlalchemy.orm import DeclarativeBase, sessionmaker
+
 from app.core.config import settings
 
+
 class Base(DeclarativeBase):
     pass
 
-engine = create_engine(settings.database_url, pool_pre_ping=True)
+
+engine = create_engine(
+    settings.database_url, pool_pre_ping=True, connect_args={"connect_timeout": 5}
+)
 SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False)
 
+
 def get_db():
     db = SessionLocal()
     try:
         yield db
+    except Exception:
+        db.rollback()
+        raise
     finally:
         db.close()