fix: auto-fix code issues (cron)

- 修复重复导入/字段
- 修复异常处理 (BaseException -> 具体异常类型)
- 修复PEP8格式问题
- 添加类型注解
- 修复tingwu_client.py缩进错误

backend/test_phase8_task2.py

@@ -96,7 +96,7 @@ def test_subscription_manager():
 
         # 获取用量汇总
         summary = manager.get_usage_summary(tenant_id)
-        print(f"✓ 用量汇总:")
+        print("✓ 用量汇总:")
         print(f"  - 总费用: ¥{summary['total_cost']:.2f}")
         for resource, data in summary['breakdown'].items():
             print(f"  - {resource}: {data['quantity']} (¥{data['cost']:.2f})")