fix: prevent "No crumbs yet" flash on page refresh

Add notesLoaded store flag set after IDB read completes. Gate the empty
state message behind it so it only shows once we know the store is empty.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/lib/stores/notes.ts

@@ -7,6 +7,7 @@ import { extractTags } from '$lib/utils/tags.js';
 export const notes = writable<Note[]>([]);
 export const currentFilter = writable<NoteFilter>('all');
 export const selectedTag = writable<string | null>(null);
+export const notesLoaded = writable(false);
 
 export const filteredNotes = derived(
 	[notes, selectedTag, currentFilter],
@@ -49,8 +50,9 @@ export async function loadNotes(filter: NoteFilter = 'all') {
 	const cached = await getAllNotes();
 	if (cached.length > 0) {
 		notes.set(cached);
-		currentFilter.set(filter);
 	}
+	currentFilter.set(filter);
+	notesLoaded.set(true);
 
 	// Then fetch from server in the background
 	try {