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/widget/WidgetGrid.svelte

@@ -1,45 +1,49 @@
 <script lang="ts">
-	import AppWidget from './AppWidget.svelte';
+	import { t } from 'svelte-i18n';
+	import WidgetRenderer from './WidgetRenderer.svelte';
 	import WidgetContainer from './WidgetContainer.svelte';
 
+	interface AppData {
+		id: string;
+		name: string;
+		url: string;
+		icon: string | null;
+		iconType: string;
+		description: string | null;
+		statuses: Array<{ status: string; responseTime: number | null }>;
+	}
+
 	interface WidgetData {
 		id: string;
 		type: string;
 		order: number;
 		config: string;
 		appId: string | null;
-		app: {
-			id: string;
-			name: string;
-			url: string;
-			icon: string | null;
-			iconType: string;
-			description: string | null;
-			statuses: Array<{ status: string; responseTime: number | null }>;
-		} | null;
+		app: AppData | null;
 	}
 
 	interface Props {
 		widgets: WidgetData[];
+		allApps?: AppData[];
 	}
 
-	let { widgets }: Props = $props();
+	let { widgets, allApps = [] }: Props = $props();
+
+	// Widgets that should span full width
+	const fullWidthTypes = new Set(['note', 'embed', 'status']);
 </script>
 
 {#if widgets.length === 0}
-	<p class="text-sm text-muted-foreground">No widgets in this section.</p>
+	<p class="text-sm text-muted-foreground">{$t('widget.no_widgets')}</p>
 {:else}
 	<div class="grid grid-cols-2 gap-3 sm:grid-cols-3 lg:grid-cols-4">
 		{#each widgets as widget (widget.id)}
-			<WidgetContainer>
-				{#if widget.type === 'app' && widget.app}
-					<AppWidget app={widget.app} />
-				{:else}
-					<div class="flex h-full items-center justify-center rounded-xl border border-border bg-card p-4">
-						<span class="text-xs text-muted-foreground">{widget.type} widget</span>
-					</div>
-				{/if}
-			</WidgetContainer>
+			{@const isFullWidth = fullWidthTypes.has(widget.type)}
+			<div class={isFullWidth ? 'col-span-2 sm:col-span-3 lg:col-span-4' : ''}>
+				<WidgetContainer>
+					<WidgetRenderer {widget} {allApps} />
+				</WidgetContainer>
+			</div>
 		{/each}
 	</div>
 {/if}