Consolidate duplicated static methods (SplitFeatures, ComputeCutDistance, IsFeatureEtch, feature ordering) from CincinnatiSheetWriter and CincinnatiPartSubprogramWriter into a shared FeatureUtils class. Move inline sub-program registry building from Post() into CincinnatiPartSubprogramWriter.BuildRegistry(). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>