Grids wrote their tracks as equal ones, with a warning. Track sizes
(fixed px, hug, fill shares) are now written as gridColumnsSizing /
gridRowsSizing, the fields the import already reads.
Checked on a synthetic grid in the incumbent (fixed 320/140/112/34/34 px
columns): written as equal tracks it came in with five equal columns and
its layers overflowing their cells; now its columns keep their sizes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>