feat(web): "You might like" Home row (#790 web client slice)

The web UI rendered a fixed set of Home sections and had no code for the
server's you_might_like_albums / you_might_like_artists (shipped in
v2026.06.11), so the row was absent in the web client. Adds it, mirroring
the Rediscover block, positioned directly under the system-playlists row.

- types.ts HomePayload: two new slices (server always emits them; web ships
  in lockstep with the server).
- +page.svelte: a "You might like" section (albums + artists scrollers) as the
  first section under the playlists row, with a "still learning your taste"
  empty state for the cold-start/gated case. Reuses existing AlbumCard /
  ArtistCard / HorizontalScrollRow.
- home.test.ts / page.test.ts: mock payloads gain the two fields.

Completes the You-might-like row across all three clients (server already
emits it; Android in v2026.06.11; web here).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/lib/api/home.test.ts

@@ -18,7 +18,9 @@ describe('home client', () => {
       rediscover_albums: [],
       rediscover_artists: [],
       most_played_tracks: [],
-      last_played_artists: []
+      last_played_artists: [],
+      you_might_like_albums: [],
+      you_might_like_artists: []
     };
     (api.get as ReturnType<typeof vi.fn>).mockResolvedValueOnce(fixture);
     const got = await listHome();

web/src/lib/api/types.ts

@@ -342,4 +342,6 @@ export type HomePayload = {
   rediscover_artists:    ArtistRef[];
   most_played_tracks:    TrackRef[];
   last_played_artists:   ArtistRef[];
+  you_might_like_albums:  AlbumRef[];
+  you_might_like_artists: ArtistRef[];
 };

web/src/routes/+page.svelte

@@ -161,6 +161,42 @@
   {:else if showSkeleton.value && !data}
     <p class="text-text-secondary">Loading…</p>
   {:else if data}
+    <!-- You might like: taste-predicted in-library albums + artists the user
+         doesn't actively spin (server section, daily-built, cold-start gated).
+         Sits directly under the system playlists row. Two scrollers like
+         Rediscover (square album vs circular artist cards). -->
+    <section class="space-y-3">
+      {#if data.you_might_like_albums.length === 0 && data.you_might_like_artists.length === 0}
+        <header>
+          <h2 class="font-display text-2xl font-medium text-text-primary">You might like</h2>
+        </header>
+        <p class="text-text-secondary">We're still learning your taste — keep listening and picks you might like will show up here.</p>
+      {:else}
+        {#if data.you_might_like_albums.length > 0}
+          <HorizontalScrollRow
+            rows={[data.you_might_like_albums]}
+            title="You might like"
+            ariaLabel="You might like albums"
+          >
+            {#snippet item(album: import('$lib/api/types').AlbumRef)}
+              <div class="w-40"><AlbumCard {album} /></div>
+            {/snippet}
+          </HorizontalScrollRow>
+        {/if}
+        {#if data.you_might_like_artists.length > 0}
+          <HorizontalScrollRow
+            rows={[data.you_might_like_artists]}
+            title={data.you_might_like_albums.length === 0 ? 'You might like' : undefined}
+            ariaLabel="You might like artists"
+          >
+            {#snippet item(artist: import('$lib/api/types').ArtistRef)}
+              <div class="w-36"><ArtistCard {artist} /></div>
+            {/snippet}
+          </HorizontalScrollRow>
+        {/if}
+      {/if}
+    </section>
+
     <!-- Recently added: 50 albums in 2 rows of 25, scrolling together -->
     <section class="space-y-3">
       {#if data.recently_added_albums.length === 0}

web/src/routes/page.test.ts

@@ -13,7 +13,9 @@ vi.mock('$lib/api/home', () => ({
         most_played_tracks: [],
         rediscover_albums: [],
         rediscover_artists: [],
-        last_played_artists: []
+        last_played_artists: [],
+        you_might_like_albums: [],
+        you_might_like_artists: []
       },
       isPending: false,
       isError: false,