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/routes/+page.server.ts

@@ -1,21 +1,27 @@
+import { redirect } from '@sveltejs/kit';
 import type { PageServerLoad, Actions } from './$types';
 import { createApiClient, requireUser } from '$lib/server/api';
-import { fetchYoutubeFiller } from '$lib/server/youtube';
+import { fetchYoutubeAlbumFiller, fetchYoutubeFiller } from '$lib/server/youtube';
 import {
 	addAlbumToPlaylistAction,
 	addTrackAction,
 	addYouTubeToPlaylistAction
 } from '$lib/server/playlistActions';
 import {
+	HOME_ALBUM_FILLER_LIMIT,
 	HOME_ALBUMS_LIMIT,
 	HOME_LATEST_PAGE_SIZE,
 	HOME_MIXES_BENTO,
+	HOME_POPULAR_FILLER_LIMIT,
 	HOME_SHELF_LIMIT,
+	HOME_TOP_MUSIC_FILLER_LIMIT,
 	YOUTUBE_FILLER_LIMIT
 } from '$lib/config';
 import { pickGreeting } from '$lib/server/greeting';
 
 export const load: PageServerLoad = async ({ locals, url, fetch }) => {
+	// This dashboard is personal; an anonymous listener goes to /explore instead.
+	if (!locals.user) redirect(302, '/explore');
 	const user = requireUser(locals, url);
 	const api = createApiClient({ fetch, accessToken: locals.accessToken ?? undefined });
 
@@ -44,7 +50,9 @@ export const load: PageServerLoad = async ({ locals, url, fetch }) => {
 		recentlyPlayedPromise
 	]);
 	const playlistItems = playlists.data?.items ?? [];
-	const latestItems = (latest.data?.items ?? []).flatMap((item) => (item.track ? [item.track] : []));
+	const latestItems = (latest.data?.items ?? []).flatMap((item) =>
+		item.track ? [item.track] : []
+	);
 
 	return {
 		greeting: pickGreeting(new Date().getHours()),
@@ -54,12 +62,37 @@ export const load: PageServerLoad = async ({ locals, url, fetch }) => {
 		playlists: playlistItems.slice(0, HOME_SHELF_LIMIT),
 		playlistsHasMore: playlistItems.length > HOME_SHELF_LIMIT,
 		newReleases: latestItems,
+		topMusicFiller: fetchYoutubeFiller(
+			api,
+			locals.accessToken,
+			HOME_TOP_MUSIC_FILLER_LIMIT,
+			undefined,
+			user.sub,
+			3
+		),
 		youtubeFiller: fetchYoutubeFiller(
 			api,
 			locals.accessToken,
 			YOUTUBE_FILLER_LIMIT,
 			undefined,
-			user.sub
+			user.sub,
+			0
+		),
+		popularFiller: fetchYoutubeFiller(
+			api,
+			locals.accessToken,
+			HOME_POPULAR_FILLER_LIMIT,
+			undefined,
+			user.sub,
+			1
+		),
+		albumFiller: fetchYoutubeAlbumFiller(
+			api,
+			locals.accessToken,
+			HOME_ALBUM_FILLER_LIMIT,
+			undefined,
+			user.sub,
+			2
 		)
 	};
 };