feat(phase2): localization EN/RU + additional widget types

- Add svelte-i18n with 224 translation keys (English + Russian)
- Language switcher in header (EN/RU toggle, persists to localStorage)
- Extract all hardcoded strings from 37 component/page files
- Add 4 new widget types: Bookmark, Note (markdown), Embed (iframe), Status
- WidgetRenderer dispatches by type, WidgetGrid supports full-width widgets
- Type-specific config forms in board editor
- Install marked for markdown rendering

src/lib/components/app/AppHealthBadge.svelte

@@ -1,4 +1,6 @@
 <script lang="ts">
+	import { t } from 'svelte-i18n';
+
 	interface Props {
 		status: string;
 	}
@@ -8,18 +10,18 @@
 	const config = $derived.by(() => {
 		switch (status) {
 			case 'online':
-				return { color: 'bg-green-500', cssClass: 'status-online', text: 'Online' };
+				return { color: 'bg-green-500', cssClass: 'status-online', textKey: 'status.online' };
 			case 'offline':
-				return { color: 'bg-red-500', cssClass: '', text: 'Offline' };
+				return { color: 'bg-red-500', cssClass: '', textKey: 'status.offline' };
 			case 'degraded':
-				return { color: 'bg-yellow-500', cssClass: '', text: 'Degraded' };
+				return { color: 'bg-yellow-500', cssClass: '', textKey: 'status.degraded' };
 			default:
-				return { color: 'bg-gray-500', cssClass: '', text: 'Unknown' };
+				return { color: 'bg-gray-500', cssClass: '', textKey: 'status.unknown' };
 		}
 	});
 </script>
 
 <span class="inline-flex items-center gap-1.5 text-xs">
 	<span class="inline-block h-2 w-2 rounded-full {config.color} {config.cssClass}"></span>
-	<span class="text-muted-foreground">{config.text}</span>
+	<span class="text-muted-foreground">{$t(config.textKey)}</span>
 </span>