chore: sync local updates

mengyamonitor-backend-client/dashboard_payload.go

@@ -0,0 +1,25 @@
+package main
+
+import "encoding/json"
+
+// BuildDashboardPayloadJSON builds the same JSON shape the browser expects (including latency).
+// collectorToCentralMs is 采集器到监控中心 TCP 建连毫秒数，失败传 -1。
+func BuildDashboardPayloadJSON(collectorToCentralMs float64) ([]byte, error) {
+	m, err := CollectMetrics()
+	if err != nil {
+		return nil, err
+	}
+	b, err := json.Marshal(m)
+	if err != nil {
+		return nil, err
+	}
+	var o map[string]any
+	if err := json.Unmarshal(b, &o); err != nil {
+		return nil, err
+	}
+	o["latency"] = map[string]any{
+		"clientToServer": collectorToCentralMs,
+		"external":       readExternalLatencies(),
+	}
+	return json.Marshal(o)
+}