- Move BuildPairParts to BestFitResult.BuildParts() instance method
- Extract BinConverter (RectanglePacking) for Part/NestItem/Bin conversions
- Extract RotationAnalysis for FindBestRotation and FindHullEdgeAngles
NestEngine reduced from 484 to 287 lines — now purely orchestration,
strategy selection, and comparison logic.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>