Introduces PartClass enum and Classify() static method that categorizes
parts as Large (exceeds half work area in either dimension), Medium
(area > 1/9 work area), or Small.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Implements static MultiPlateNester.SortItems with BoundingBoxArea and Size sort orders, covered by two passing xUnit tests.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
