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/PlayerBar.test.ts

@@ -1,7 +1,8 @@
 import { afterEach, beforeEach, 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';
 
 // Mutable state the mocked store reads from.
 const state = vi.hoisted(() => ({
@@ -44,22 +45,9 @@ vi.mock('$lib/player/store.svelte', () => ({
   toggleQueueDrawer: 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());
 
-vi.mock('$lib/api/quarantine', () => ({
-  flagTrack: vi.fn(),
-  unflagTrack: vi.fn(),
-  listMyQuarantine: vi.fn().mockResolvedValue([]),
-  createMyQuarantineQuery: vi.fn()
-}));
+vi.mock('$lib/api/quarantine', () => emptyQuarantineMock());
 
 import PlayerBar from './PlayerBar.svelte';
 import {