SubProgramCalls are now treated as standalone features in the Cincinnati
post-processor. SplitByRapids emits them as single-element features
instead of splitting on rapids within sub-programs. A nest-level hole
sub-program registry deduplicates by content and assigns post numbers.
Sheet writers emit M98 calls with X/Y offsets for hole features, and
hole sub-program definitions are written after part sub-programs.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>