refactor: move GpuEvaluatorFactory to OpenNest.Gpu project

GPU factory logic belongs with the GPU implementation, not the UI.
Changed from internal to public and updated namespace to OpenNest.Gpu.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

OpenNest.Gpu/GpuEvaluatorFactory.cs

@@ -3,11 +3,10 @@ using System.Diagnostics;
 using ILGPU;
 using ILGPU.Runtime;
 using OpenNest.Engine.BestFit;
-using OpenNest.Gpu;
 
-namespace OpenNest
+namespace OpenNest.Gpu
 {
-    internal static class GpuEvaluatorFactory
+    public static class GpuEvaluatorFactory
     {
         private static bool _probed;
         private static bool _gpuAvailable;

OpenNest/Actions/ActionClone.cs

@@ -4,6 +4,7 @@ using System.Linq;
 using System.Windows.Forms;
 using OpenNest.Controls;
 using OpenNest.Geometry;
+using OpenNest.Gpu;
 
 namespace OpenNest.Actions
 {

OpenNest/Actions/ActionFillArea.cs

@@ -1,6 +1,7 @@
 using System.ComponentModel;
 using System.Windows.Forms;
 using OpenNest.Controls;
+using OpenNest.Gpu;
 
 namespace OpenNest.Actions
 {

OpenNest/Forms/MainForm.cs

@@ -6,6 +6,7 @@ using System.Reflection;
 using System.Windows.Forms;
 using OpenNest.Actions;
 using OpenNest.Collections;
+using OpenNest.Gpu;
 using OpenNest.Geometry;
 using OpenNest.IO;
 using OpenNest.Properties;