fix(home): uniform card heights in the Your Libraries row

MediaCard derives its artwork aspect ratio from the item, so a music
library rendered aspect-square (144px tall at w-36) next to video
libraries at aspect-video (81px), leaving the home row ragged.

Add an optional `aspect` prop that overrides the derived ratio, and pass
aspect="video" from the home Libraries strip. Unset, behaviour is
unchanged, so the /library overview grid and the media carousels keep
their per-type ratios. Artwork already uses object-cover, so square music
art crops rather than distorts.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/routes/+page.svelte

@@ -159,12 +159,15 @@
     {#if shortcutLibraries.length > 0}
       <div>
         <h2 class="text-xl font-bold text-white mb-4 px-4">Your Libraries</h2>
-        <div class="flex gap-4 overflow-x-auto px-4 pb-2">
+        <div class="flex gap-4 overflow-x-auto px-4 pb-2 items-start">
           {#each shortcutLibraries as lib (lib.id)}
             <div class="flex-shrink-0">
+              <!-- Uniform 16:9 artwork so music (square) and video libraries
+                   line up at the same height in this mixed row. -->
               <MediaCard
                 item={lib}
                 size="medium"
+                aspect="video"
                 onclick={() => handleLibraryClick(lib)}
               />
             </div>