Cards can now be reordered within a column (not just moved between columns); a blue drop-line shows exactly where the card will land. onMove gains a toIndex arg — onMove(id, toColumn, toIndex) — so consumers can persist a shared order. BREAKING: onMove signature changed. Release 0.10.0.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>