feat: redesign web interface to match aonsoku layout

Replace the early prototype UI with a darker Aonsoku-inspired shell featuring a compact top bar, library sidebar, command palette, settings overlay, dense track list, artists table, albums grid, and a bottom player bar. Add a supporting albums browse endpoint so the frontend can render the same navigation shape without faking data.

internal/library/service.go

@@ -173,6 +173,34 @@ func (s *Service) RecentAlbums(ctx context.Context, limit int) ([]Album, error)
 	return albums, rows.Err()
 }
 
+func (s *Service) Albums(ctx context.Context, limit int) ([]Album, error) {
+	rows, err := s.db.QueryContext(
+		ctx,
+		`SELECT al.id, al.artist_id, a.name, al.title, COALESCE(al.year, 0), COUNT(t.id) AS track_count, COALESCE(al.cover_art_id, '')
+		 FROM albums al
+		 JOIN artists a ON a.id = al.artist_id
+		 LEFT JOIN tracks t ON t.album_id = al.id
+		 GROUP BY al.id, al.artist_id, a.name, al.title, al.year, al.cover_art_id
+		 ORDER BY al.year DESC, al.title ASC
+		 LIMIT ?`,
+		limit,
+	)
+	if err != nil {
+		return nil, fmt.Errorf("query all albums: %w", err)
+	}
+	defer rows.Close()
+
+	var albums []Album
+	for rows.Next() {
+		var album Album
+		if err := rows.Scan(&album.ID, &album.ArtistID, &album.ArtistName, &album.Title, &album.Year, &album.TrackCount, &album.CoverArtID); err != nil {
+			return nil, fmt.Errorf("scan all albums: %w", err)
+		}
+		albums = append(albums, album)
+	}
+	return albums, rows.Err()
+}
+
 func (s *Service) AlbumByID(ctx context.Context, id string) (AlbumDetail, error) {
 	var album AlbumDetail