fix: harden rule and forwarding edge cases

internal/ingest/alert_forward.go

@@ -72,7 +72,12 @@ func postAlertPayload(cfg *config.AlertForwardConf, path string, payload []byte)
 	if cfg.InternalKey != "" {
 		req.Header.Set("X-Internal-Key", cfg.InternalKey)
 	}
-	client := &http.Client{Timeout: 10 * time.Second}
+	client := &http.Client{
+		Timeout: 10 * time.Second,
+		CheckRedirect: func(_ *http.Request, _ []*http.Request) error {
+			return http.ErrUseLastResponse
+		},
+	}
 	resp, err := client.Do(req)
 	if err != nil {
 		return fmt.Errorf("发送 Alert 转发请求失败：%w", err)