Cutoff features now substitute plate-edge coordinates with #SheetWidthVariable
and #SheetLengthVariable references. Vertical cutoffs at Y=plate_width emit
Y#110, horizontal cutoffs at X=plate_length emit X#111. Segmented cutoffs
only substitute the edge coordinate, interior segment endpoints stay literal.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>