Add anonymous listening support and redesign web-player UI

Backend:
- Expose GET /config/playback so the frontend can detect whether
  anonymous listening is enabled without requiring auth
- Wire anonymous access through track streaming and YouTube resolve flows

Frontend:
- Allow browsing/listening without a session when the backend enables it
- Redesign Inicio, Sidebar and top bar with a new dark theme, typography,
  and layout (top bar with live quick-search, sticky/blurred on scroll)
- Populate Top música, Popular and Recomendados with real Musify +
  YouTube Music data instead of placeholders
- Various shape, spacing, color and animation refinements across the
  redesigned components

web-player/src/lib/config.ts

@@ -13,4 +13,8 @@ export const HOME_ALBUMS_LIMIT = 12;
 export const HOME_MIXES_BENTO = 5;
 export const HOME_SHELF_LIMIT = 6;
 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 PLAYLIST_PICKER_PAGE_SIZE = 50;