feat(phase2): phase 6 - integration & polish

Fix all build/type/lint errors, write 60 new tests (175 total),
update seed with new widget types and team board permissions,
install missing svelte-i18n dependency, fix DynamicIcon for Svelte 5.

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

@@ -5,7 +5,7 @@
 	import { invalidateAll } from '$app/navigation';
 	import DraggableBoard from '$lib/components/board/DraggableBoard.svelte';
 	import BoardAccessControl from '$lib/components/board/BoardAccessControl.svelte';
-	import { WidgetType } from '$lib/utils/constants.js';
+
 
 	let { data }: { data: PageData } = $props();