fix: bound long-lived cache state

app/helper/webpush.py

@@ -0,0 +1,12 @@
+from typing import Any
+
+from pywebpush import WebPushException
+
+
+def is_webpush_subscription_gone(error: WebPushException) -> bool:
+    """
+    判断 WebPush 订阅是否已经在浏览器或推送服务侧失效。
+    """
+    response: Any = getattr(error, "response", None)
+    status_code = getattr(response, "status_code", None) or getattr(response, "status", None)
+    return status_code in {404, 410}