fix: leave etch/scribe marks out of nesting geometry

Every nesting-geometry consumer filtered only rapids, so scribe/etch
moves counted as part material. An etch tick that ends a hair outside
the outline (PEP bend ticks start on the notch edge) made the part
"open geometry leaving the material region": the job validator threw
and every built-in engine plus Gpt6Astra crashed on real PEP jobs
(PT75, drawing 4980 A01 PT77). Marks are only on the surface, so they
should never affect placement, collision, area, or validation.

- SpecialLayers.IsMaterial excludes Rapid and Scribe; used by drawing
  area, canonical angle, part collision, PartGeometry, plate perimeter,
  best-fit/pair evaluation, rotation analysis, GPU evaluators, and both
  validators. Timing, display, splitting and posts still see marks.
- ConvertGeometry also maps the saved SCRIBE layer name to Scribe, so
  programs rebuilt from stored entities keep their marks.
- NestReader repairs older files (e.g. PepNestExport output) whose
  programs saved etch as cut moves while source entities kept SCRIBE.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

OpenNest.IO/NestReader.cs

@@ -7,6 +7,7 @@ using System.Linq;
 using System.Text.Json;
 using OpenNest.Bending;
 using OpenNest.CNC;
+using OpenNest.Converters;
 using OpenNest.Engine.BestFit;
 using OpenNest.Geometry;
 using static OpenNest.IO.NestFormat;
@@ -215,6 +216,17 @@ namespace OpenNest.IO
                 {
                     drawing.SourceEntities = entitySet.entities;
                     drawing.SuppressedEntityIds = entitySet.suppressed;
+
+                    // Older files saved etch marks as cut moves; restore their Scribe layer so
+                    // nesting ignores them. The program was mutated in place, so refresh.
+                    if (
+                        drawing.Program != null
+                        && ScribeLayerRepair.Apply(drawing.Program, drawing.SourceEntities, drawing.Source.Offset) > 0
+                    )
+                    {
+                        drawing.UpdateArea();
+                        drawing.RecomputeCanonicalAngle();
+                    }
                 }
 
                 map[d.Id] = drawing;