refactor(core): move clamps into OpenNest.Clamps

Co-Authored-By: Claude Fable 5.2 <noreply@anthropic.com>

OpenNest.WinForms.Tests/Controls/ActionClampEditTests.cs

@@ -2,6 +2,7 @@ using System.Drawing;
 using System.Reflection;
 using System.Windows.Forms;
 using OpenNest.Actions;
+using OpenNest.Clamps;
 using OpenNest.Controls;
 using OpenNest.Geometry;
 using static OpenNest.WinForms.Tests.FormTesting;

OpenNest.WinForms.Tests/Controls/PlateViewClampMenuTests.cs

@@ -1,4 +1,5 @@
 using OpenNest.Actions;
+using OpenNest.Clamps;
 using OpenNest.Controls;
 using OpenNest.Geometry;