fix: preserve circle rotation direction through geometry round-trip

Circle.Rotation was lost in three places, causing reversed circles to
still offset inward instead of outward:
- ConvertGeometry.AddCircle hardcoded CCW instead of using circle.Rotation
- ConvertProgram.AddArcMove created Circle without setting Rotation from arc
- Shape.OffsetOutward/OffsetInward copied Circle without setting Rotation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

OpenNest.Core/Converters/ConvertProgram.cs

@@ -106,7 +106,7 @@ namespace OpenNest.Converters
             var layer = ConvertLayer(arcMove.Layer);
 
             if (startAngle.IsEqualTo(endAngle))
-                geometry.Add(new Circle(center, radius) { Layer = layer, Color = layer.Color });
+                geometry.Add(new Circle(center, radius) { Layer = layer, Color = layer.Color, Rotation = arcMove.Rotation });
             else
                 geometry.Add(new Arc(center, radius, startAngle, endAngle, arcMove.Rotation == RotationType.CW) { Layer = layer, Color = layer.Color });