feat: collect and report 1-min load average

internal/sender/payload.go

@@ -10,11 +10,12 @@ type SnapshotPayload struct {
 	MemAvg  float64 `json:"mem_avg"`
 	DiskAvg float64 `json:"disk_avg"`
 	Uptime  uint64  `json:"uptime"`
+	Load    float64 `json:"load"`
 
 	HostID      string `json:"host_id,omitempty"`
 	Environment string `json:"environment,omitempty"`
 
-	// Optional — only present when DB monitoring is enabled.
+	// Optional. only present when DB monitoring is enabled.
 	// DBDriver is a numeric identifier: 1=mysql/mariadb 2=postgres 3=redis 4=mongodb 5=sqlite
 	DBDriver         *uint8   `json:"db_driver,omitempty"`
 	DBConnPct        *float64 `json:"db_conn_pct,omitempty"`