feat: add etch mark entities from bend lines to CNC program pipeline

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>

OpenNest.Api/NestRunner.cs

@@ -35,7 +35,8 @@ public static class NestRunner
             if (!importer.GetGeometry(part.DxfPath, out var geometry) || geometry.Count == 0)
                 throw new InvalidOperationException($"Failed to import DXF: {part.DxfPath}");
 
-            var pgm = ConvertGeometry.ToProgram(geometry);
+            var normalized = ShapeProfile.NormalizeEntities(geometry);
+            var pgm = ConvertGeometry.ToProgram(normalized);
             var name = Path.GetFileNameWithoutExtension(part.DxfPath);
             var drawing = new Drawing(name);
             drawing.Program = pgm;