1.添加定时任务(每天凌晨四点处理redis记录的删除，存储入mysql持久化操作)

2.修复了prompt中没有用户输入信息的bug
3.优化了更新类接口代码(删除了db.add()代码)

app/background_tasks.py

@@ -0,0 +1,31 @@
+from .dependencies.database import get_db
+from .dependencies.redis import get_redis
+from .dependencies.logger import get_logger
+from .models import Session
+from datetime import datetime, timedelta
+
+logger = get_logger()
+
+def updating_redis_cache():
+    db = next(get_db())
+    redis = get_redis()
+    current_time = datetime.now()
+    two_days_ago = current_time - timedelta(days=2)
+    db.begin()
+    try:
+        expired_sessions = db.query(Session.id).filter(Session.last_activity < two_days_ago).all()
+        for session_id_tuple in expired_sessions:
+            session_id = session_id_tuple[0]
+            session_content = redis.get(session_id)
+            if session_content is None:
+                logger.error(f"Session {session_id} not found in Redis cache")
+                continue
+            redis.delete(session_id)
+            db.query(Session).filter(Session.id == session_id).update({'content':session_content})
+        db.commit()
+    except Exception as e:
+        db.rollback()
+        raise e
+    finally:
+        db.close()
+    logger.info("Redis cache updated successfully")