fix: auto-fix code issues (cron)

- 修复未定义名称 (F821): 添加缺失的导入
  - ExportEntity, ExportRelation, ExportTranscript
  - WorkflowManager, PluginManager, OpsManager
  - urllib.parse
- 修复裸异常捕获: except: → except Exception:
- 删除 __pycache__ 缓存文件
- 格式化代码 (PEP8)

自动化修复: 23个问题
剩余需手动处理: 104个行长度问题 (E501)

backend/security_manager.py

@@ -297,9 +297,7 @@ class SecurityManager:
         """)
 
         # 创建索引
-        cursor.execute(
-            "CREATE INDEX IF NOT EXISTS idx_audit_logs_user ON audit_logs(user_id)"
-        )
+        cursor.execute("CREATE INDEX IF NOT EXISTS idx_audit_logs_user ON audit_logs(user_id)")
         cursor.execute(
             "CREATE INDEX IF NOT EXISTS idx_audit_logs_resource "
             "ON audit_logs(resource_type, resource_id)"