refactor(web/test): default svelte-query mock in vitest.setup; remove from 34 files (B3)

web/src/routes/playlists/playlists.test.ts

@@ -8,14 +8,6 @@ vi.mock('$lib/api/playlists', () => ({
   createPlaylist: vi.fn().mockResolvedValue({ id: 'p-new', name: 'X' })
 }));
 
-vi.mock('@tanstack/svelte-query', async (orig) => {
-  const actual = (await orig()) as Record<string, unknown>;
-  return {
-    ...actual,
-    useQueryClient: () => ({ invalidateQueries: vi.fn().mockResolvedValue(undefined) })
-  };
-});
-
 vi.mock('$app/navigation', () => ({ goto: vi.fn() }));
 
 import PlaylistsPage from './+page.svelte';