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/routes/boards/[boardId]/+page.svelte

@@ -1,4 +1,5 @@
 <script lang="ts">
+	import { t } from 'svelte-i18n';
 	import type { PageData } from './$types.js';
 	import Board from '$lib/components/board/Board.svelte';
 	import BoardHeader from '$lib/components/board/BoardHeader.svelte';
@@ -7,7 +8,7 @@
 </script>
 
 <svelte:head>
-	<title>{data.board.name} — Web App Launcher</title>
+	<title>{data.board.name} — {$t('app_title')}</title>
 </svelte:head>
 
 <div class="p-6">
@@ -20,6 +21,6 @@
 			canEdit={data.canEdit}
 		/>
 
-		<Board sections={data.board.sections} />
+		<Board sections={data.board.sections} allApps={data.allApps} />
 	</div>
 </div>