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/routes/artists/[id]/artist.test.ts

@@ -1,8 +1,8 @@
 import { afterEach, describe, expect, test, vi } from 'vitest';
 import { render, screen } from '@testing-library/svelte';
 import { flushSync } from 'svelte';
-import { readable } from 'svelte/store';
 import { mockQuery } from '../../../test-utils/query';
+import { emptyLikesMock } from '../../../test-utils/mocks/likes';
 import type { ArtistDetail, AlbumRef } from '$lib/api/types';
 
 const state = vi.hoisted(() => ({ pageParams: { id: 'abc' } as Record<string, string> }));
@@ -19,15 +19,7 @@ vi.mock('$lib/api/queries', () => ({
   createArtistQuery: vi.fn()
 }));
 
-vi.mock('$lib/api/likes', () => ({
-  createLikedIdsQuery: () => readable({
-    data: { track_ids: [], album_ids: [], artist_ids: [] },
-    isPending: false,
-    isError: false
-  }),
-  likeEntity: vi.fn(),
-  unlikeEntity: vi.fn()
-}));
+vi.mock('$lib/api/likes', () => emptyLikesMock());
 
 import ArtistPage from './+page.svelte';
 import { createArtistQuery } from '$lib/api/queries';