refactor(scheduler): 优化定时任务配置和时间处理

- 支持CHECK_INTERVAL_HOURS设置为0以禁用密钥检查任务
- 调整日志清理任务执行时间从凌晨3点改为0点
- 移除timezone依赖，使用本地时间处理
- 优化代码格式和导入顺序
- 为配置编辑器添加CHECK_INTERVAL_HOURS输入验证
- 改进UI布局，为关键配置项添加警告提示

app/service/error_log/error_log_service.py

@@ -1,4 +1,4 @@
-from datetime import datetime, timedelta, timezone
+from datetime import datetime, timedelta
 from typing import Any, Dict, List, Optional
 
 from sqlalchemy import delete, func, select
@@ -28,7 +28,7 @@ async def delete_old_error_logs():
         )
         return
 
-    cutoff_date = datetime.now(timezone.utc) - timedelta(days=days_to_keep)
+    cutoff_date = datetime.now() - timedelta(days=days_to_keep)
 
     logger.info(
         f"Attempting to delete error logs older than {days_to_keep} days (before {cutoff_date.strftime('%Y-%m-%d %H:%M:%S %Z')})."