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/lib/components/section/DraggableSection.svelte

@@ -44,7 +44,7 @@
 
 	let {
 		section,
-		boardId,
+		boardId: _boardId = '',
 		apps,
 		onWidgetsUpdate,
 		addWidgetSectionId,
@@ -54,6 +54,9 @@
 		onDeleteWidget
 	}: Props = $props();
 
+	// boardId reserved for future per-section API calls
+	void _boardId;
+
 	let widgets = $state<WidgetData[]>([...section.widgets]);
 
 	// Keep local state in sync when parent data changes