Lets multiple stacked HorizontalScrollRow instances render under a
single visible heading by passing title: "" to the second-row-onward
instances. Combined with the existing shared-controller support, this
gives us multi-row scrollers without a new widget.
Used in the next commit's home rewrite for Recently added (2 rows)
and Most played (3 rows).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
HorizontalScrollRow takes an optional shared ScrollController so
multi-row sections (Most played: 3 rows) couple their scroll like the
web HorizontalScrollRow.svelte. Cards fall back to the synced
album-fallback.svg when coverUrl is empty.
bvandeusen