feat(nav): add cursor-pointer and tooltip to notification bell

Extract bellLabel as $derived to DRY up aria-label and title.
Add cursor-pointer globally to button via @layer base so Tailwind
preflight reset doesn't override the browser default.

Closes #344

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

frontend/src/lib/components/NotificationBell.svelte

@@ -48,6 +48,12 @@ function handleKeydown(event: KeyboardEvent) {
 	}
 }
 
+const bellLabel = $derived(
+	stream.unreadCount > 0
+		? m.notification_bell_unread_label({ count: stream.unreadCount })
+		: m.notification_bell_label()
+);
+
 function attachBellButton(node: HTMLButtonElement) {
 	bellButtonEl = node;
 	return () => {
@@ -72,12 +78,11 @@ onDestroy(() => {
 		{@attach attachBellButton}
 		type="button"
 		onclick={toggleDropdown}
-		aria-label={stream.unreadCount > 0
+		aria-label={bellLabel}
-			? m.notification_bell_unread_label({ count: stream.unreadCount })
+		title={bellLabel}
-			: m.notification_bell_label()}
 		aria-expanded={open}
 		aria-haspopup="true"
-		class="relative rounded-sm p-2 text-white/65 transition-colors hover:bg-white/10 hover:text-white focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring"
+		class="relative cursor-pointer rounded-sm p-2 text-white/65 transition-colors hover:bg-white/10 hover:text-white focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring"
 	>
 		<svg
 			xmlns="http://www.w3.org/2000/svg"

frontend/src/lib/components/NotificationBell.svelte.spec.ts

@@ -55,6 +55,34 @@ async function openDropdownAndClickFirstNotification() {
 	notifButton.click();
 }
 
+describe('NotificationBell — cursor and tooltip', () => {
+	it('bell button has cursor-pointer class', async () => {
+		render(NotificationBell);
+		const btn = document.querySelector<HTMLButtonElement>('button[aria-haspopup="true"]')!;
+		expect(btn.classList.contains('cursor-pointer')).toBe(true);
+	});
+
+	it('bell button title equals aria-label when unreadCount is 0', async () => {
+		mockNotificationList.value = [];
+		render(NotificationBell);
+		const btn = document.querySelector<HTMLButtonElement>('button[aria-haspopup="true"]')!;
+		expect(btn.getAttribute('title')).toBe('Benachrichtigungen');
+		expect(btn.getAttribute('aria-label')).toBe(btn.getAttribute('title'));
+	});
+
+	it('bell button title equals aria-label when unreadCount is 3', async () => {
+		mockNotificationList.value = [
+			makeNotification({ id: 'n1' }),
+			makeNotification({ id: 'n2' }),
+			makeNotification({ id: 'n3' })
+		];
+		render(NotificationBell);
+		const btn = document.querySelector<HTMLButtonElement>('button[aria-haspopup="true"]')!;
+		expect(btn.getAttribute('title')).toBe('3 ungelesene Benachrichtigungen');
+		expect(btn.getAttribute('aria-label')).toBe(btn.getAttribute('title'));
+	});
+});
+
 describe('NotificationBell', () => {
 	it('handleMarkRead navigates to URL including annotationId when notification has annotationId', async () => {
 		mockNotificationList.value = [makeNotification({ annotationId: 'annot-1' })];

frontend/src/routes/layout.css

@@ -365,6 +365,11 @@
 		text-underline-offset: 4px;
 	}
 
+	/* Tailwind preflight resets cursor on *, overriding the browser default for buttons */
+	button {
+		cursor: pointer;
+	}
+
 	/* Fallback focus ring for any interactive element not styled with ring-focus-ring */
 	:focus-visible {
 		outline: 2px solid var(--c-focus-ring);