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/board/Board.svelte

@@ -1,4 +1,5 @@
 <script lang="ts">
+	import { t } from 'svelte-i18n';
 	import Section from '$lib/components/section/Section.svelte';
 
 	interface SectionData {
@@ -25,21 +26,32 @@
 		}>;
 	}
 
-	interface Props {
-		sections: SectionData[];
+	interface AppData {
+		id: string;
+		name: string;
+		url: string;
+		icon: string | null;
+		iconType: string;
+		description: string | null;
+		statuses: Array<{ status: string; responseTime: number | null }>;
 	}
 
-	let { sections }: Props = $props();
+	interface Props {
+		sections: SectionData[];
+		allApps?: AppData[];
+	}
+
+	let { sections, allApps = [] }: Props = $props();
 </script>
 
 <div class="space-y-6">
 	{#if sections.length === 0}
 		<div class="rounded-xl border border-border bg-card/50 p-12 text-center">
-			<p class="text-muted-foreground">This board has no sections yet.</p>
+			<p class="text-muted-foreground">{$t('board.no_sections')}</p>
 		</div>
 	{:else}
 		{#each sections as section (section.id)}
-			<Section {section} />
+			<Section {section} {allApps} />
 		{/each}
 	{/if}
 </div>