test(notification): add goto mock and tighten selector in NotificationDropdown spec

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

frontend/src/lib/notification/NotificationDropdown.svelte.test.ts

@@ -1,8 +1,11 @@
 import { describe, it, expect, vi, afterEach } from 'vitest';
 import { cleanup, render } from 'vitest-browser-svelte';
 import { page } from 'vitest/browser';
+import { goto } from '$app/navigation';
 import NotificationDropdown from './NotificationDropdown.svelte';
 
+vi.mock('$app/navigation', () => ({ goto: vi.fn() }));
+
 afterEach(cleanup);
 
 const makeNotification = (overrides: Record<string, unknown> = {}) => ({
@@ -164,9 +167,10 @@ describe('NotificationDropdown', () => {
 			}
 		});
 
-		await page.getByRole('link').click();
+		await page.getByRole('link', { name: /alle aktivitäten|view all/i }).click();
 
 		expect(onClose).toHaveBeenCalledOnce();
+		expect(goto).toHaveBeenCalledWith('/aktivitaeten');
 	});
 
 	it('renders MENTION items with the mention verb text', async () => {