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/CompactTrackCard.test.ts

@@ -2,20 +2,12 @@ import { afterEach, describe, expect, test, vi } from 'vitest';
 import { render, screen, fireEvent } from '@testing-library/svelte';
 import type { TrackRef } from '$lib/api/types';
 import { readable } from 'svelte/store';
+import { emptyLikesMock } from '../../test-utils/mocks/likes';
+import { emptyQuarantineMock } from '../../test-utils/mocks/quarantine';
 
-vi.mock('$lib/api/likes', () => ({
-  createLikedIdsQuery: () =>
-    readable({ data: { track_ids: [], album_ids: [], artist_ids: [] }, isPending: false, isError: false }),
-  likeEntity: vi.fn().mockResolvedValue(undefined),
-  unlikeEntity: vi.fn().mockResolvedValue(undefined)
-}));
+vi.mock('$lib/api/likes', () => emptyLikesMock());
 
-vi.mock('$lib/api/quarantine', () => ({
-  flagTrack: vi.fn().mockResolvedValue({}),
-  unflagTrack: vi.fn().mockResolvedValue(undefined),
-  listMyQuarantine: vi.fn().mockResolvedValue([]),
-  createMyQuarantineQuery: () => readable({ data: [], isPending: false, isError: false })
-}));
+vi.mock('$lib/api/quarantine', () => emptyQuarantineMock());
 
 vi.mock('$lib/api/admin/tracks', () => ({
   removeTrack: vi.fn().mockResolvedValue({ deleted_track_id: 't1' })