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.server.ts

@@ -1,6 +1,7 @@
 import { error } from '@sveltejs/kit';
 import type { PageServerLoad } from './$types.js';
 import * as boardService from '$lib/server/services/boardService.js';
+import * as appService from '$lib/server/services/appService.js';
 import * as permissionService from '$lib/server/services/permissionService.js';
 import { EntityType, PermissionLevel, UserRole } from '$lib/utils/constants.js';
 import { isBoardGuestAccessible } from '$lib/server/middleware/guestAccess.js';
@@ -32,7 +33,10 @@ export const load: PageServerLoad = async ({ params, locals }) => {
 
 	try {
 		// findBoardById includes sections -> widgets -> app -> statuses
-		const board = await boardService.findBoardById(boardId);
+		const [board, allApps] = await Promise.all([
+			boardService.findBoardById(boardId),
+			appService.findAll()
+		]);
 
 		// Determine if user can edit this board
 		let canEdit = false;
@@ -50,7 +54,7 @@ export const load: PageServerLoad = async ({ params, locals }) => {
 			}
 		}
 
-		return { board, canEdit };
+		return { board, canEdit, allApps };
 	} catch (err) {
 		const message = err instanceof Error ? err.message : 'Board not found';
 		if (message.includes('not found')) {