feat: bring over the albums, explore and player work from the worktree

Moves the remaining uncommitted work: the home gets quick mixes and a
"Tus álbumes" shelf, saving a YouTube album now goes through
addYoutubeAlbumToPlaylistAction instead of the SaveYouTubeAlbum command,
and UserAlbum drops its unused ExternalId.

The mixes section keeps its current shape (no refresh action, no badge,
hidden when empty) rather than the older version the worktree carried.

web-player/src/lib/components/ui/Input.svelte

@@ -37,7 +37,7 @@
 <div class="relative w-full">
 	{#if Icon}
 		<span class="pointer-events-none absolute inset-y-0 left-4 grid place-items-center text-muted">
-			<Icon class="h-4 w-4" />
+			<Icon class="h-5 w-5" />
 		</span>
 	{/if}
 	<input
@@ -52,7 +52,7 @@
 		{autocomplete}
 		{oninput}
 		bind:value
-		class="w-full rounded-control border border-line bg-surface py-3 text-base text-fg transition placeholder:text-muted focus:border-accent/50 focus:outline-none {Icon
+		class="w-full rounded-control bg-surface py-3 text-base text-fg transition placeholder:text-muted focus:border-accent/50 focus:outline-none {Icon
 			? 'pr-4 pl-11'
 			: 'px-4'} {klass}"
 	/>