feat(alerts): add alert for failed systemd services (#2173)

Adds a user-configurable "Failed Services" alert that notifies when any
tracked systemd service enters the failed state, and again when all services
recover.

---------

Signed-off-by: Martin Stenröse <martin@stenrose.se>
Co-authored-by: henrygd <hank@henrygd.me>

internal/site/src/lib/alerts.ts

@@ -1,5 +1,5 @@
 import { t } from "@lingui/core/macro"
-import { CpuIcon, HardDriveIcon, MemoryStickIcon, ServerIcon } from "lucide-react"
+import { CpuIcon, HardDriveIcon, MemoryStickIcon, ServerCrashIcon, ServerIcon } from "lucide-react"
 import type { RecordSubscription } from "pocketbase"
 import { EthernetIcon, GpuIcon } from "@/components/ui/icons"
 import { $alerts } from "@/lib/stores"
@@ -104,6 +104,15 @@ export const alertInfo: Record<string, AlertInfo> = {
 		start: 20,
 		invert: true,
 	},
+	SystemdFailed: {
+		name: () => t`Failed Services`,
+		unit: "",
+		icon: ServerCrashIcon,
+		desc: () => t`Triggers when any systemd service enters the failed state`,
+		triggeredDesc: () => t`One or more services are in the failed state`,
+		/** Fires on first observation - the agent only polls systemd every 10 minutes */
+		noDuration: true,
+	},
 } as const
 
 /** Helper to manage user alerts */