refactor(web): sweep test files to use empty likes/quarantine mocks (#375)

Replaces duplicated inline vi.mock('$lib/api/likes', ...) blocks with
the emptyLikesMock() helper, and (where previously left in working
tree by a parallel quarantine sweep) rolls in the matching
emptyQuarantineMock() switchovers in the same files.

Together with commit dd67f28 — which already swept the four search/*
test files for likes — this completes the 18 likes-mock conversions
called out in #375.

LikeButton.test.ts kept inline — it uses a state-driven mock to
assert the toggle behavior.

SKIPPED:
- liked.test.ts: re-exports createLikedTracksInfiniteQuery and the
  album/artist variants that emptyLikesMock() doesn't provide.
- playlist.test.ts: hand-rolled { subscribe, data } stub instead of
  readable(...) — different store contract.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

web/src/lib/components/ArtistCard.test.ts

@@ -1,5 +1,6 @@
 import { afterEach, describe, expect, test, vi } from 'vitest';
 import { render, screen, fireEvent } from '@testing-library/svelte';
+import { emptyLikesMock } from '../../test-utils/mocks/likes';
 import type { ArtistRef, TrackRef } from '$lib/api/types';
 
 vi.mock('$lib/api/client', () => ({
@@ -12,15 +13,7 @@ vi.mock('$lib/player/store.svelte', () => ({
 vi.mock('$lib/api/artists', () => ({
   listArtistTracks: vi.fn().mockResolvedValue([])
 }));
-vi.mock('$lib/api/likes', async () => {
-  const { readable } = await import('svelte/store');
-  return {
-    createLikedIdsQuery: () =>
-      readable({ data: { track_ids: [], album_ids: [], artist_ids: [] }, isPending: false, isError: false }),
-    likeEntity: vi.fn().mockResolvedValue(undefined),
-    unlikeEntity: vi.fn().mockResolvedValue(undefined)
-  };
-});
+vi.mock('$lib/api/likes', () => emptyLikesMock());
 import ArtistCard from './ArtistCard.svelte';
 import { api } from '$lib/api/client';
 import { playQueue } from '$lib/player/store.svelte';