AlbumCard gains optional `width` (default 140 keeps horizontal lists
unchanged) and `titleMaxLines` (default 1) so callers can let the
title wrap to a second line. Cover sizes to width - 16 instead of a
hardcoded 124, so the card scales down cleanly when a narrower cell
width is passed in.
Artist detail grid: switch to 3 columns. LayoutBuilder computes the
cell width from the available width so AlbumCard sizes to the cell
exactly (no overflow). cellH = cover + gap + 2-line title + artist
line + small fudge — tight enough that there's no visible gap below
the card, tall enough to fit a wrapped title.