feat: ship host metrics as a first-party in-process plugin

plugins/host-metrics/frontend/cards/UptimeCard.tsx

@@ -0,0 +1,28 @@
+import { Clock } from "lucide-react";
+import { useTranslation } from "react-i18next";
+import type { ServerMetrics } from "@/main-axios";
+import { MetricCard } from "@/components/metric-card";
+
+export function UptimeCard({ metrics }: { metrics: ServerMetrics | null }) {
+  const { t } = useTranslation();
+  const uptime = metrics?.uptime;
+
+  return (
+    <MetricCard
+      title={t("hostMetrics.uptime")}
+      icon={<Clock className="size-3.5" />}
+    >
+      <div className="flex h-full flex-col justify-center gap-2">
+        <span className="text-2xl font-bold leading-none text-accent-brand md:text-3xl">
+          {uptime?.formatted ?? "N/A"}
+        </span>
+        {uptime?.seconds != null && (
+          <span className="font-mono text-xs text-muted-foreground">
+            {Math.floor(uptime.seconds).toLocaleString()}{" "}
+            {t("hostMetrics.seconds")}
+          </span>
+        )}
+      </div>
+    </MetricCard>
+  );
+}