fix: apply managed Nginx public entry without service restart

backend/internal/api/identity_gateway.go

@@ -38,6 +38,26 @@ func authGatewayPort(publicBase string) (int, error) {
 	return port, nil
 }
 
+func checkAuthGatewayChange(oldBase, newBase string) error {
+	if oldBase == "" || oldBase == newBase {
+		return nil
+	}
+	port, err := authGatewayPort(oldBase)
+	if err != nil {
+		return err
+	}
+	if port != 0 {
+		return &activeAuthEntry{}
+	}
+	return nil
+}
+
+type activeAuthEntry struct{}
+
+func (*activeAuthEntry) Error() string {
+	return "运行中的 OIDC 专线仍使用旧公网地址，请先停止或迁移专线"
+}
+
 type gatewayConflict struct{}
 
 func (*gatewayConflict) Error() string {