fix: auto-fix code issues (cron)

- 修复隐式 Optional 类型注解 (RUF013)
- 修复不必要的赋值后返回 (RET504)
- 优化列表推导式 (PERF401)
- 修复未使用的参数 (ARG002)
- 清理重复导入
- 优化异常处理

backend/test_phase8_task8.py

@@ -129,7 +129,9 @@ class TestOpsManager:
 
             # 更新告警规则
             updated_rule = self.manager.update_alert_rule(
-                rule1.id, threshold=85.0, description="更新后的描述",
+                rule1.id,
+                threshold=85.0,
+                description="更新后的描述",
             )
             assert updated_rule.threshold == 85.0
             self.log(f"Updated alert rule threshold to {updated_rule.threshold}")
@@ -421,7 +423,9 @@ class TestOpsManager:
 
             # 模拟扩缩容评估
             event = self.manager.evaluate_scaling_policy(
-                policy_id=policy.id, current_instances=3, current_utilization=0.85,
+                policy_id=policy.id,
+                current_instances=3,
+                current_utilization=0.85,
             )
 
             if event:
@@ -439,7 +443,8 @@ class TestOpsManager:
             with self.manager._get_db() as conn:
                 conn.execute("DELETE FROM scaling_events WHERE tenant_id = ?", (self.tenant_id,))
                 conn.execute(
-                    "DELETE FROM auto_scaling_policies WHERE tenant_id = ?", (self.tenant_id,),
+                    "DELETE FROM auto_scaling_policies WHERE tenant_id = ?",
+                    (self.tenant_id,),
                 )
                 conn.commit()
             self.log("Cleaned up auto scaling test data")
@@ -530,7 +535,8 @@ class TestOpsManager:
 
             # 发起故障转移
             event = self.manager.initiate_failover(
-                config_id=config.id, reason="Primary region health check failed",
+                config_id=config.id,
+                reason="Primary region health check failed",
             )
 
             if event:
@@ -638,7 +644,9 @@ class TestOpsManager:
             # 生成成本报告
             now = datetime.now()
             report = self.manager.generate_cost_report(
-                tenant_id=self.tenant_id, year=now.year, month=now.month,
+                tenant_id=self.tenant_id,
+                year=now.year,
+                month=now.month,
             )
 
             self.log(f"Generated cost report: {report.id}")
@@ -691,7 +699,8 @@ class TestOpsManager:
                 )
                 conn.execute("DELETE FROM idle_resources WHERE tenant_id = ?", (self.tenant_id,))
                 conn.execute(
-                    "DELETE FROM resource_utilizations WHERE tenant_id = ?", (self.tenant_id,),
+                    "DELETE FROM resource_utilizations WHERE tenant_id = ?",
+                    (self.tenant_id,),
                 )
                 conn.execute("DELETE FROM cost_reports WHERE tenant_id = ?", (self.tenant_id,))
                 conn.commit()