feat(ui): phase 5 — graphs, widgets, theming, PWA, boards, i18n

P5a: 24h uptime bar strip + latency chart on monitor detail, iframe
embed widget, generic JSON-path widget, accent/wallpaper/custom CSS
settings, PWA manifest + service worker, demo GIF.

P5b: transport picker + per-transport fields + test button in
settings; per-monitor alert-rule fields in dialogs.

P5c: container cpu/mem columns, SMART/ZFS/GPU sections on system
detail, subdomains section on domain detail.

P5d: login/setup page + auth middleware client handling, board
switcher + /b/:slug routes, full string extraction to typed t() keys
with {param} interpolation, complete cs locale, language select.

Authored By: TDvorak <[email protected]>

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/frontend/src/widgets/system.tsx

@@ -1,6 +1,7 @@
 import type { WidgetData } from "@/widgets";
 import type { Item } from "@/types";
 import { cn } from "@/lib/utils";
+import { t } from "@/i18n";
 
 // Board tile for a monitored system: status dot + cpu/mem/disk mini bars.
 // config.systemId binds it; data comes from the system fetcher.
@@ -47,7 +48,7 @@ export function SystemWidget({ item, data, error }: {
 				{typeof data?.name === "string" ? data.name : item.name}
 			</span>
 			{error ? (
-				<span className="shrink-0 font-mono text-[10.5px] text-text-faint">err</span>
+				<span className="shrink-0 font-mono text-[10.5px] text-text-faint">{t("widget.err")}</span>
 			) : (
 				<span className="flex shrink-0 items-center gap-2">
 					{bar(cpu, "cpu")}