feat: move PushDirection enum to OpenNest.Core

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

OpenNest.Core/OpenNest.Core.csproj

@@ -88,6 +88,7 @@
     <Compile Include="Converters\ConvertMode.cs" />
     <Compile Include="Nest.cs" />
     <Compile Include="Part.cs" />
+    <Compile Include="PushDirection.cs" />
     <Compile Include="Collections\ObservableList.cs" />
     <Compile Include="Plate.cs" />
     <Compile Include="CNC\Program.cs" />

OpenNest.Core/PushDirection.cs

@@ -1,4 +1,4 @@
-
+
 namespace OpenNest
 {
     public enum PushDirection

OpenNest/OpenNest.csproj

@@ -175,7 +175,6 @@
     <Compile Include="MdiExtensions.cs" />
     <Compile Include="MainApp.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="PushDirection.cs" />
     <Compile Include="ToolStripRenderer.cs" />
     <Compile Include="SelectionType.cs" />
     <Compile Include="Win32.cs" />