feat(web): wire LikeButton into TrackRow, AlbumCard, ArtistRow, PlayerBar

Heart appears on every entity rendering surface. ArtistRow restructured
to a <div> with the link as a positioned overlay so the heart button
can nest without invalid <button>-in-<a> markup. Shell nav grows a
'Liked' entry pointing at /library/liked.

web/src/lib/components/AlbumCard.svelte

@@ -3,6 +3,7 @@
   import { FALLBACK_COVER } from '$lib/media/covers';
   import { api } from '$lib/api/client';
   import { enqueueTracks } from '$lib/player/store.svelte';
+  import LikeButton from './LikeButton.svelte';
 
   let { album }: { album: AlbumRef } = $props();
 
@@ -35,10 +36,13 @@
       <div class="text-xs text-text-secondary">{album.year}</div>
     {/if}
   </a>
-  <button
-    type="button"
-    aria-label="Add to queue"
-    onclick={onAddClick}
-    class="absolute right-2 top-2 rounded-full bg-surface/80 px-2 py-1 text-sm text-text-secondary hover:text-text-primary focus-visible:ring-2 focus-visible:ring-accent"
-  >+</button>
+  <div class="absolute right-2 top-2 flex gap-1">
+    <LikeButton entityType="album" entityId={album.id} />
+    <button
+      type="button"
+      aria-label="Add to queue"
+      onclick={onAddClick}
+      class="rounded-full bg-surface/80 px-2 py-1 text-sm text-text-secondary hover:text-text-primary focus-visible:ring-2 focus-visible:ring-accent"
+    >+</button>
+  </div>
 </div>

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

@@ -2,6 +2,7 @@ import { afterEach, describe, expect, test, vi } from 'vitest';
 import { render, screen, fireEvent } from '@testing-library/svelte';
 import type { AlbumRef, AlbumDetail, TrackRef } from '$lib/api/types';
 import { FALLBACK_COVER } from '$lib/media/covers';
+import { readable } from 'svelte/store';
 
 vi.mock('$lib/api/client', () => ({
   api: { get: vi.fn() }
@@ -10,6 +11,21 @@ vi.mock('$lib/player/store.svelte', () => ({
   enqueueTracks: vi.fn()
 }));
 
+vi.mock('$lib/api/likes', () => ({
+  createLikedIdsQuery: () => readable({
+    data: { track_ids: [], album_ids: [], artist_ids: [] },
+    isPending: false,
+    isError: false
+  }),
+  likeEntity: vi.fn(),
+  unlikeEntity: vi.fn()
+}));
+
+vi.mock('@tanstack/svelte-query', async (orig) => {
+  const actual = (await orig()) as Record<string, unknown>;
+  return { ...actual, useQueryClient: () => ({}) };
+});
+
 import AlbumCard from './AlbumCard.svelte';
 import { api } from '$lib/api/client';
 import { enqueueTracks } from '$lib/player/store.svelte';

web/src/lib/components/ArtistRow.svelte

@@ -1,5 +1,6 @@
 <script lang="ts">
   import type { ArtistRef } from '$lib/api/types';
+  import LikeButton from './LikeButton.svelte';
 
   let { artist }: { artist: ArtistRef } = $props();
 
@@ -7,17 +8,22 @@
   const countLabel = $derived(artist.album_count === 1 ? '1 album' : `${artist.album_count} albums`);
 </script>
 
-<a
-  href={`/artists/${artist.id}`}
-  class="flex items-center gap-3 border-b border-border px-3 py-3 hover:bg-surface-hover focus-visible:ring-2 focus-visible:ring-accent"
->
+<div class="relative flex items-center gap-3 border-b border-border px-3 py-3 hover:bg-surface-hover">
+  <a
+    href={`/artists/${artist.id}`}
+    class="absolute inset-0 focus-visible:ring-2 focus-visible:ring-accent"
+    aria-label={artist.name}
+  ></a>
   <span
-    class="flex h-10 w-10 shrink-0 items-center justify-center rounded-full bg-surface font-semibold"
+    class="flex h-10 w-10 shrink-0 items-center justify-center rounded-full bg-surface font-semibold relative"
     aria-hidden="true"
   >
     {initial}
   </span>
-  <span class="flex-1 truncate">{artist.name}</span>
-  <span class="text-sm text-text-secondary">{countLabel}</span>
-  <span class="text-text-secondary" aria-hidden="true">›</span>
-</a>
+  <span class="flex-1 truncate relative">{artist.name}</span>
+  <span class="text-sm text-text-secondary relative">{countLabel}</span>
+  <span class="relative">
+    <LikeButton entityType="artist" entityId={artist.id} />
+  </span>
+  <span class="text-text-secondary relative" aria-hidden="true">›</span>
+</div>

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

@@ -1,8 +1,24 @@
-import { describe, expect, test } from 'vitest';
+import { describe, expect, test, vi } from 'vitest';
 import { render, screen } from '@testing-library/svelte';
+import { readable } from 'svelte/store';
 import ArtistRow from './ArtistRow.svelte';
 import type { ArtistRef } from '$lib/api/types';
 
+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('@tanstack/svelte-query', async (orig) => {
+  const actual = (await orig()) as Record<string, unknown>;
+  return { ...actual, useQueryClient: () => ({}) };
+});
+
 const artist: ArtistRef = { id: 'abc', name: 'alice', album_count: 12 };
 
 describe('ArtistRow', () => {
@@ -11,14 +27,14 @@ describe('ArtistRow', () => {
 
     const link = screen.getByRole('link');
     expect(link).toHaveAttribute('href', '/artists/abc');
-    expect(link).toHaveTextContent('alice');
-    expect(link).toHaveTextContent('12 albums');
-    expect(link).toHaveTextContent('A'); // initial letter
+    expect(screen.getByText('alice')).toBeInTheDocument();
+    expect(screen.getByText('12 albums')).toBeInTheDocument();
+    expect(screen.getByText('A')).toBeInTheDocument();
   });
 
   test('singular "1 album" when album_count is 1', () => {
     render(ArtistRow, { props: { artist: { ...artist, album_count: 1 } } });
-    expect(screen.getByRole('link')).toHaveTextContent('1 album');
+    expect(screen.getByText('1 album')).toBeInTheDocument();
   });
 
   test('empty name still renders a safe initial', () => {

web/src/lib/components/PlayerBar.svelte

@@ -6,6 +6,7 @@
   } from '$lib/player/store.svelte';
   import { formatDuration } from '$lib/media/duration';
   import { FALLBACK_COVER } from '$lib/media/covers';
+  import LikeButton from './LikeButton.svelte';
 
   const current = $derived(player.current);
 
@@ -48,7 +49,7 @@
           onerror={onCoverError}
         />
       </a>
-      <div class="min-w-0">
+      <div class="min-w-0 flex-1">
         <div class="truncate text-sm font-medium">{current.title}</div>
         <a
           href={`/artists/${current.artist_id}`}
@@ -57,6 +58,7 @@
           {current.artist_name}
         </a>
       </div>
+      <LikeButton entityType="track" entityId={current.id} />
     </div>
 
     <!-- Center: seek row + transport row -->

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

@@ -1,6 +1,7 @@
 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';
 
 // Mutable state the mocked store reads from.
 const state = vi.hoisted(() => ({
@@ -40,6 +41,21 @@ vi.mock('$lib/player/store.svelte', () => ({
   playQueue:     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('@tanstack/svelte-query', async (orig) => {
+  const actual = (await orig()) as Record<string, unknown>;
+  return { ...actual, useQueryClient: () => ({}) };
+});
+
 import PlayerBar from './PlayerBar.svelte';
 import {
   togglePlay, skipNext, skipPrev, seekTo, setVolume,

web/src/lib/components/Shell.svelte

@@ -22,9 +22,10 @@
   }
 
   const navItems = [
-    { href: '/',          label: 'Library' },
-    { href: '/search',    label: 'Search' },
-    { href: '/playlists', label: 'Playlists' }
+    { href: '/',              label: 'Library' },
+    { href: '/library/liked', label: 'Liked' },
+    { href: '/search',        label: 'Search' },
+    { href: '/playlists',     label: 'Playlists' }
   ];
 </script>
 

web/src/lib/components/TrackRow.svelte

@@ -2,6 +2,7 @@
   import type { TrackRef } from '$lib/api/types';
   import { formatDuration } from '$lib/media/duration';
   import { playQueue, enqueueTrack } from '$lib/player/store.svelte';
+  import LikeButton from './LikeButton.svelte';
 
   type PlayHandler = (tracks: TrackRef[], index: number) => void;
 
@@ -41,12 +42,13 @@
   aria-label={track.title}
   onclick={onRowClick}
   onkeydown={onRowKey}
-  class="grid w-full cursor-pointer grid-cols-[32px_1fr_auto_auto] items-center gap-4 px-3 py-2 text-left text-sm odd:bg-surface/50 hover:bg-surface focus-visible:outline focus-visible:outline-2 focus-visible:outline-accent"
+  class="grid w-full cursor-pointer grid-cols-[32px_1fr_auto_auto_auto] items-center gap-4 px-3 py-2 text-left text-sm odd:bg-surface/50 hover:bg-surface focus-visible:outline focus-visible:outline-2 focus-visible:outline-accent"
 >
   <span class="text-right tabular-nums text-text-secondary">
     {track.track_number ?? '—'}
   </span>
   <span class="truncate">{track.title}</span>
+  <LikeButton entityType="track" entityId={track.id} />
   <button
     type="button"
     aria-label="Add to queue"

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

@@ -1,12 +1,28 @@
 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';
 
 vi.mock('$lib/player/store.svelte', () => ({
   playQueue: vi.fn(),
   enqueueTrack: vi.fn()
 }));
 
+vi.mock('$lib/api/likes', () => ({
+  createLikedIdsQuery: () => readable({
+    data: { track_ids: [], album_ids: [], artist_ids: [] },
+    isPending: false,
+    isError: false
+  }),
+  likeEntity: vi.fn(),
+  unlikeEntity: vi.fn()
+}));
+
+vi.mock('@tanstack/svelte-query', async (orig) => {
+  const actual = (await orig()) as Record<string, unknown>;
+  return { ...actual, useQueryClient: () => ({}) };
+});
+
 import TrackRow from './TrackRow.svelte';
 import { playQueue, enqueueTrack } from '$lib/player/store.svelte';