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

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

web-player/src/lib/format.ts

@@ -5,6 +5,13 @@ export function fmtTime(seconds: number): string {
 	return `${minutes}:${rest < 10 ? '0' : ''}${rest}`;
 }
 
+export function fmtDurationLong(seconds: number): string {
+	const total = Math.max(0, Math.floor(seconds || 0));
+	const hours = Math.floor(total / 3600);
+	const minutes = Math.floor((total % 3600) / 60);
+	return hours > 0 ? `${hours} h ${minutes} min` : `${minutes} min`;
+}
+
 const dateFormatter = new Intl.DateTimeFormat('es', { dateStyle: 'medium' });
 
 export function fmtDate(value: string | number | Date): string {