Etch marks for up bends are now real geometry entities on an ETCH layer
instead of being drawn dynamically. They flow through the full pipeline:
entities → FilterPanel layers → ConvertGeometry (tagged as Scribe) →
post-processor sequencing before cut geometry.
Also includes ShapeProfile normalization (CW perimeter, CCW cutouts)
applied consistently across all import paths, and inward offset support
for cutout shapes in overlap/offset polygon calculations.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Introduces OpenNest.Core/Bending/ with Bend and BendDirection types as
the foundation for bend line detection. Includes 6 passing unit tests.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
