feat(web): pair scroll arrows beside section title; bleed scroller to viewport edge

Restructures HorizontalScrollRow so paired arrows sit in a flex header
beside an optional section title (instead of absolute-positioned at the
row's left/right edges). Adds margin-right: -1rem to the row so the
scroller's items extend to the viewport's right edge, escaping Shell's
p-4 padding. The header bar keeps its right gutter so titles align with
the rest of the page content.

Home page passes 'title' to the first row of each section; subsequent
rows in multi-row sections render arrow-only headers.

web/src/lib/components/HorizontalScrollRow.svelte

@@ -5,10 +5,12 @@
   let {
     items,
     item,
+    title,
     ariaLabel
   }: {
     items: T[];
     item?: Snippet<[T, number]>;
+    title?: string;
     ariaLabel?: string;
   } = $props();
 
@@ -37,16 +39,34 @@
   $effect(() => { refreshMetrics(); });
 </script>
 
-<div class="row relative" aria-label={ariaLabel}>
-  <button
-    type="button"
-    class="arrow arrow-left"
-    aria-label="Scroll left"
-    onclick={() => page(-1)}
-    disabled={atStart}
-  >
-    <ChevronLeft size={16} strokeWidth={1} />
-  </button>
+<div class="row" aria-label={ariaLabel}>
+  <header class="row-header">
+    {#if title}
+      <h2 class="font-display text-2xl font-medium text-text-primary">{title}</h2>
+    {:else}
+      <span></span>
+    {/if}
+    <div class="arrows">
+      <button
+        type="button"
+        class="arrow"
+        aria-label="Scroll left"
+        onclick={() => page(-1)}
+        disabled={atStart}
+      >
+        <ChevronLeft size={16} strokeWidth={1} />
+      </button>
+      <button
+        type="button"
+        class="arrow"
+        aria-label="Scroll right"
+        onclick={() => page(1)}
+        disabled={atEnd}
+      >
+        <ChevronRight size={16} strokeWidth={1} />
+      </button>
+    </div>
+  </header>
 
   <div
     bind:this={scroller}
@@ -58,20 +78,27 @@
       {@render item?.(it, i)}
     {/each}
   </div>
-
-  <button
-    type="button"
-    class="arrow arrow-right"
-    aria-label="Scroll right"
-    onclick={() => page(1)}
-    disabled={atEnd}
-  >
-    <ChevronRight size={16} strokeWidth={1} />
-  </button>
 </div>
 
 <style>
-  .row { padding: 0 36px; }
+  /* Bleed the row past the parent's right padding (16px from Shell's p-4)
+     so the scroller's items extend to the viewport's right edge. */
+  .row {
+    margin-right: -1rem;
+  }
+  .row-header {
+    display: flex;
+    align-items: center;
+    justify-content: space-between;
+    /* Re-add the right gutter so the header stays aligned with the rest
+       of the page content (the scroller below remains full-bleed). */
+    padding-right: 1rem;
+    margin-bottom: 0.5rem;
+  }
+  .arrows {
+    display: flex;
+    gap: 0.5rem;
+  }
   .scroller {
     scroll-snap-type: x mandatory;
     scrollbar-width: thin;
@@ -81,9 +108,6 @@
     scroll-snap-align: start;
   }
   .arrow {
-    position: absolute;
-    top: 50%;
-    transform: translateY(-50%);
     width: 32px;
     height: 32px;
     border-radius: 9999px;
@@ -93,14 +117,7 @@
     align-items: center;
     justify-content: center;
     border: 1px solid var(--fs-pewter);
-    z-index: 1;
   }
   .arrow:hover:not(:disabled) { color: var(--fs-parchment); }
   .arrow:disabled { opacity: 0.3; cursor: not-allowed; }
-  .arrow-left  { left: 0; }
-  .arrow-right { right: 0; }
-  @media (hover: hover) {
-    .arrow { opacity: 0; transition: opacity 150ms ease; }
-    .row:hover .arrow { opacity: 1; }
-  }
 </style>

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

@@ -29,4 +29,14 @@ describe('HorizontalScrollRow', () => {
     expect(spy).toHaveBeenCalledWith({ left: expect.any(Number), behavior: 'smooth' });
     expect(spy.mock.calls[0][0].left).toBeGreaterThan(0);
   });
+
+  test('renders title as a heading when prop is provided', () => {
+    render(HorizontalScrollRow, { props: { items: ['a'], title: 'My section' } });
+    expect(screen.getByRole('heading', { name: 'My section' })).toBeInTheDocument();
+  });
+
+  test('omits heading when title prop is absent', () => {
+    render(HorizontalScrollRow, { props: { items: ['a'] } });
+    expect(screen.queryByRole('heading')).not.toBeInTheDocument();
+  });
 });

web/src/routes/+page.svelte

@@ -30,14 +30,18 @@
   {:else if data}
     <!-- Recently added: 50 albums in 2 rows of 25 -->
     <section class="space-y-3">
-      <header>
-        <h2 class="font-display text-2xl font-medium text-text-primary">Recently added</h2>
-      </header>
       {#if data.recently_added_albums.length === 0}
+        <header>
+          <h2 class="font-display text-2xl font-medium text-text-primary">Recently added</h2>
+        </header>
         <p class="text-text-secondary">Nothing added yet. Scan a folder via the server's config.</p>
       {:else}
         {#each chunk(data.recently_added_albums, 25) as row, i (i)}
-          <HorizontalScrollRow items={row} ariaLabel="Recently added row {i + 1}">
+          <HorizontalScrollRow
+            items={row}
+            title={i === 0 ? 'Recently added' : undefined}
+            ariaLabel="Recently added row {i + 1}"
+          >
             {#snippet item(album: import('$lib/api/types').AlbumRef)}
               <div class="w-44"><AlbumCard {album} /></div>
             {/snippet}
@@ -48,21 +52,29 @@
 
     <!-- Rediscover: albums + artists -->
     <section class="space-y-3">
-      <header>
-        <h2 class="font-display text-2xl font-medium text-text-primary">Rediscover</h2>
-      </header>
       {#if data.rediscover_albums.length === 0 && data.rediscover_artists.length === 0}
+        <header>
+          <h2 class="font-display text-2xl font-medium text-text-primary">Rediscover</h2>
+        </header>
         <p class="text-text-secondary">No forgotten favourites yet. Like some albums or artists to fill this in.</p>
       {:else}
         {#if data.rediscover_albums.length > 0}
-          <HorizontalScrollRow items={data.rediscover_albums} ariaLabel="Rediscover albums">
+          <HorizontalScrollRow
+            items={data.rediscover_albums}
+            title="Rediscover"
+            ariaLabel="Rediscover albums"
+          >
             {#snippet item(album: import('$lib/api/types').AlbumRef)}
               <div class="w-44"><AlbumCard {album} /></div>
             {/snippet}
           </HorizontalScrollRow>
         {/if}
         {#if data.rediscover_artists.length > 0}
-          <HorizontalScrollRow items={data.rediscover_artists} ariaLabel="Rediscover artists">
+          <HorizontalScrollRow
+            items={data.rediscover_artists}
+            title={data.rediscover_albums.length === 0 ? 'Rediscover' : undefined}
+            ariaLabel="Rediscover artists"
+          >
             {#snippet item(artist: import('$lib/api/types').ArtistRef)}
               <div class="w-36"><ArtistCard {artist} /></div>
             {/snippet}
@@ -73,14 +85,18 @@
 
     <!-- Most played: 75 tracks in 3 rows of 25 -->
     <section class="space-y-3">
-      <header>
-        <h2 class="font-display text-2xl font-medium text-text-primary">Most played</h2>
-      </header>
       {#if data.most_played_tracks.length === 0}
+        <header>
+          <h2 class="font-display text-2xl font-medium text-text-primary">Most played</h2>
+        </header>
         <p class="text-text-secondary">No plays to draw from. Listen to something.</p>
       {:else}
         {#each chunk(data.most_played_tracks, 25) as row, i (i)}
-          <HorizontalScrollRow items={row} ariaLabel="Most played row {i + 1}">
+          <HorizontalScrollRow
+            items={row}
+            title={i === 0 ? 'Most played' : undefined}
+            ariaLabel="Most played row {i + 1}"
+          >
             {#snippet item(track: import('$lib/api/types').TrackRef, idx: number)}
               <CompactTrackCard
                 {track}
@@ -95,13 +111,17 @@
 
     <!-- Last played artists -->
     <section class="space-y-3">
-      <header>
-        <h2 class="font-display text-2xl font-medium text-text-primary">Last played</h2>
-      </header>
       {#if data.last_played_artists.length === 0}
+        <header>
+          <h2 class="font-display text-2xl font-medium text-text-primary">Last played</h2>
+        </header>
         <p class="text-text-secondary">No recent plays.</p>
       {:else}
-        <HorizontalScrollRow items={data.last_played_artists} ariaLabel="Last played artists">
+        <HorizontalScrollRow
+          items={data.last_played_artists}
+          title="Last played"
+          ariaLabel="Last played artists"
+        >
           {#snippet item(artist: import('$lib/api/types').ArtistRef)}
             <div class="w-36"><ArtistCard {artist} /></div>
           {/snippet}