Add likes, follows and playlist visibility; redesign web-player UI

Backend:
- New Likes feature (toggle/get liked tracks) and endpoints
- User follow/unfollow, listening stats, public user profile
- Playlist visibility (public/private) support
- Various auth and DTO/response adjustments to support the above

Frontend (web-player):
- New design system pass: theme tokens/mode (light/dark), glass menu,
  tabs bar, player dock/extras/queue components, mix tiles, artist link
- New routes: Liked, public user profile (/u/[id]), likes API proxy
- Search refactor: shared SearchBox component used by TopBar and
  MobileHeader (search now reachable on mobile), live results as you
  type instead of requiring Enter, dropped the "Buscando…" quick-result
  preview
- Removed now-unused components (MobileNav, CoverBadge, MixBentoTile,
  PlayPauseOverlay, SuggestionsTable, userDirectory)
- Design handoff reference docs added under web-player/design_handoff_musify_player
  and web-player/docs/design-system-refactor-plan.md

web-player/src/lib/components/TrackContextMenu.svelte

@@ -22,6 +22,7 @@
 	import ListPlus from '@lucide/svelte/icons/list-plus';
 	import ChevronRight from '@lucide/svelte/icons/chevron-right';
 	import PlaylistArt from '$lib/components/ui/PlaylistArt.svelte';
+	import GlassMenu from '$lib/components/ui/GlassMenu.svelte';
 
 	interface Props {
 		menu: ContextMenuState;
@@ -48,24 +49,21 @@
 		onClose();
 	}}
 ></div>
-<div
-	class="fixed z-40 w-60 rounded-panel border border-line bg-elevated p-1.5 shadow-menu"
-	style="left:{menu.x}px; top:{menu.y}px;"
->
+<GlassMenu class="fixed z-40 w-60" style="left:{menu.x}px; top:{menu.y}px;">
 	<button
 		type="button"
 		onclick={onAddToQueue}
-		class="flex w-full items-center gap-3 rounded-control px-2 py-2.5 text-left text-sm text-fg-2 transition hover:bg-hover"
+		class="flex w-full items-center gap-3 rounded-control px-2 py-2.5 text-left text-[13.5px] font-medium text-fg-2 transition hover:bg-hover"
 	>
-		<ListPlus class="h-5 w-5 shrink-0" strokeWidth={2} />
-		<span class="text-base">Reproducir a continuación</span>
+		<ListPlus class="h-[18px] w-[18px] shrink-0" strokeWidth={2} />
+		<span>Reproducir a continuación</span>
 	</button>
 	{#if playlists.length > 0}
 		<div class="group/addmenu relative">
 			<div
-				class="flex items-center gap-3 rounded-control px-2 py-2.5 text-sm text-fg-2 transition group-hover/addmenu:bg-hover"
+				class="flex items-center gap-3 rounded-control px-2 py-2.5 text-[13.5px] font-medium text-fg-2 transition group-hover/addmenu:bg-hover"
 			>
-				<span class="flex-1 cursor-default text-base">Añadir a una playlist</span>
+				<span class="flex-1 cursor-default">Añadir a una playlist</span>
 				<ChevronRight class="h-4 w-4 shrink-0 text-fg-3" />
 			</div>
 			<div
@@ -99,7 +97,7 @@
 								{/if}
 								<button
 									type="submit"
-									class="flex w-full items-center gap-3 rounded-control px-2 py-2.5 text-left text-base text-fg transition hover:bg-hover"
+									class="flex w-full items-center gap-3 rounded-control px-2 py-2.5 text-left text-[13.5px] font-medium text-fg transition hover:bg-hover"
 								>
 									<PlaylistArt
 										playlistId={playlist.id}
@@ -116,4 +114,4 @@
 			</div>
 		</div>
 	{/if}
-</div>
+</GlassMenu>