Add 5m and 10m load avg alerts and table values (#816)

Co-authored-by: henrygd <hank@henrygd.me>

beszel/internal/alerts/alerts.go

@@ -47,6 +47,8 @@ type SystemAlertStats struct {
 	NetSent      float64            `json:"ns"`
 	NetRecv      float64            `json:"nr"`
 	Temperatures map[string]float32 `json:"t"`
+	LoadAvg5     float64            `json:"l5"`
+	LoadAvg15    float64            `json:"l15"`
 }
 
 type SystemAlertData struct {

beszel/internal/alerts/alerts_system.go

@@ -54,6 +54,12 @@ func (am *AlertManager) HandleSystemAlerts(systemRecord *core.Record, data *syst
 			}
 			val = data.Info.DashboardTemp
 			unit = "°C"
+		case "LoadAvg5":
+			val = data.Info.LoadAvg5
+			unit = ""
+		case "LoadAvg15":
+			val = data.Info.LoadAvg15
+			unit = ""
 		}
 
 		triggered := alertRecord.GetBool("triggered")
@@ -190,6 +196,10 @@ func (am *AlertManager) HandleSystemAlerts(systemRecord *core.Record, data *syst
 					}
 					alert.mapSums[key] += temp
 				}
+			case "LoadAvg5":
+				alert.val += stats.LoadAvg5
+			case "LoadAvg15":
+				alert.val += stats.LoadAvg15
 			default:
 				continue
 			}
@@ -247,6 +257,10 @@ func (am *AlertManager) sendSystemAlert(alert SystemAlertData) {
 	if alert.name == "Disk" {
 		alert.name += " usage"
 	}
+	// format LoadAvg5 and LoadAvg15
+	if after, ok := strings.CutPrefix(alert.name, "LoadAvg"); ok {
+		alert.name = after + "m Load"
+	}
 
 	// make title alert name lowercase if not CPU
 	titleAlertName := alert.name