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.Mcp/Tools/InputTools.cs

@@ -1,5 +1,6 @@
 using ModelContextProtocol.Server;
 using OpenNest.Converters;
+using OpenNest.Geometry;
 using OpenNest.IO;
 using OpenNest.Shapes;
 using System.ComponentModel;
@@ -103,7 +104,8 @@ namespace OpenNest.Mcp.Tools
             if (geometry.Count == 0)
                 return "Error: no geometry found in DXF file";
 
-            var pgm = ConvertGeometry.ToProgram(geometry);
+            var normalized = ShapeProfile.NormalizeEntities(geometry);
+            var pgm = ConvertGeometry.ToProgram(normalized);
 
             if (pgm == null)
                 return "Error: failed to convert geometry to program";