feat(web/m7-377): album detail header gets LikeButton + Play/Shuffle row

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/src/routes/albums/[id]/+page.svelte

@@ -1,14 +1,17 @@
 <script lang="ts">
+  import { Play, Shuffle } from 'lucide-svelte';
   import { page } from '$app/state';
   import { createAlbumQuery } from '$lib/api/queries';
   import { pageTitle } from '$lib/branding';
   import TrackRow from '$lib/components/TrackRow.svelte';
   import LibrarySkeleton from '$lib/components/LibrarySkeleton.svelte';
   import ApiErrorBanner from '$lib/components/ApiErrorBanner.svelte';
+  import LikeButton from '$lib/components/LikeButton.svelte';
   import { useDelayed } from '$lib/utils/useDelayed.svelte';
   import { formatDuration } from '$lib/media/duration';
   import { FALLBACK_COVER } from '$lib/media/covers';
   import type { ApiError } from '$lib/api/client';
+  import { playQueue } from '$lib/player/store.svelte';
 
   const id = $derived(page.params.id ?? '');
   const queryStore = $derived(createAlbumQuery(id));
@@ -22,6 +25,39 @@
   function onCoverError(e: Event) {
     (e.currentTarget as HTMLImageElement).src = FALLBACK_COVER;
   }
+
+  let isStartingPlay = $state(false);
+
+  function shuffleArr<T>(items: T[]): T[] {
+    const arr = items.slice();
+    for (let i = arr.length - 1; i > 0; i--) {
+      const j = Math.floor(Math.random() * (i + 1));
+      [arr[i], arr[j]] = [arr[j], arr[i]];
+    }
+    return arr;
+  }
+
+  function onPlay() {
+    const data = query.data;
+    if (isStartingPlay || !data || data.tracks.length === 0) return;
+    isStartingPlay = true;
+    try {
+      playQueue(data.tracks, 0);
+    } finally {
+      isStartingPlay = false;
+    }
+  }
+
+  function onShuffle() {
+    const data = query.data;
+    if (isStartingPlay || !data || data.tracks.length === 0) return;
+    isStartingPlay = true;
+    try {
+      playQueue(shuffleArr(data.tracks), 0);
+    } finally {
+      isStartingPlay = false;
+    }
+  }
 </script>
 
 <svelte:head>
@@ -55,8 +91,11 @@
         loading="lazy"
         onerror={onCoverError}
       />
-      <div class="flex-1 space-y-1">
-        <h1 class="text-3xl font-semibold">{album.title}</h1>
+      <div class="flex-1 space-y-2">
+        <div class="flex items-center gap-3">
+          <h1 class="font-display text-2xl font-medium text-text-primary">{album.title}</h1>
+          <LikeButton entityType="album" entityId={album.id} size="lg" />
+        </div>
         <p>
           <a href={`/artists/${album.artist_id}`} class="hover:underline">{album.artist_name}</a>
         </p>
@@ -67,6 +106,28 @@
           {album.track_count} {album.track_count === 1 ? 'track' : 'tracks'}
           · {formatDuration(album.duration_sec)}
         </p>
+        <div class="flex items-center gap-2 pt-2">
+          <button
+            type="button"
+            aria-label={`Play ${album.title}`}
+            onclick={onPlay}
+            disabled={isStartingPlay || album.tracks.length === 0}
+            class="flex items-center gap-2 rounded-md bg-accent px-4 py-2 text-sm font-medium text-text-primary hover:opacity-90 focus-visible:ring-2 focus-visible:ring-accent disabled:opacity-50"
+          >
+            <Play size={16} strokeWidth={1.5} fill="currentColor" />
+            Play
+          </button>
+          <button
+            type="button"
+            aria-label={`Shuffle ${album.title}`}
+            onclick={onShuffle}
+            disabled={isStartingPlay || album.tracks.length === 0}
+            class="flex items-center gap-2 rounded-md border border-border bg-surface px-4 py-2 text-sm font-medium text-text-primary hover:border-accent focus-visible:ring-2 focus-visible:ring-accent disabled:opacity-50"
+          >
+            <Shuffle size={16} strokeWidth={1.5} />
+            Shuffle
+          </button>
+        </div>
       </div>
     </header>