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/config.ts

@@ -9,12 +9,13 @@ export const LIBRARY_PICKER_PAGE_SIZE = 50;
 export const EXPLORE_ALBUMS_PAGE_SIZE = 10;
 export const EXPLORE_ALBUMS_LIMIT = 18;
 export const HOME_LATEST_PAGE_SIZE = 10;
-export const HOME_ALBUMS_LIMIT = 12;
-export const HOME_MIXES_BENTO = 5;
+export const HOME_MIXES_LIMIT = 6;
 export const HOME_SHELF_LIMIT = 6;
+export const HOME_CONTINUE_LIMIT = 6;
+export const HOME_SPOTLIGHT_TRACKS_LIMIT = 5;
 export const YOUTUBE_FILLER_LIMIT = 27;
-export const HOME_TOP_MUSIC_FILLER_LIMIT = 10;
 export const HOME_POPULAR_FILLER_LIMIT = 10;
-export const HOME_POPULAR_MAX = 5;
-export const HOME_ALBUM_FILLER_LIMIT = 8;
+export const HOME_POPULAR_MAX = 8;
 export const PLAYLIST_PICKER_PAGE_SIZE = 50;
+export const LIKED_TRACKS_PAGE_SIZE = 500;
+export const EXPLORE_USERS_LIMIT = 12;