refactor(core): move clamps into OpenNest.Clamps

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

OpenNest.IO.Tests/ClampEdgePersistenceTests.cs

@@ -1,6 +1,7 @@
 using System.IO.Compression;
 using System.Text;
 using System.Text.Json.Nodes;
+using OpenNest.Clamps;
 using OpenNest.Geometry;
 using static OpenNest.IO.Tests.NestArchiveJson;
 

OpenNest.IO.Tests/ClampRailPersistenceTests.cs

@@ -2,6 +2,7 @@ using System.IO.Compression;
 using System.Text;
 using System.Text.Json;
 using System.Text.Json.Nodes;
+using OpenNest.Clamps;
 using OpenNest.Geometry;
 using static OpenNest.IO.Tests.NestArchiveJson;
 

OpenNest.IO.Tests/ClampZonePersistenceTests.cs

@@ -1,5 +1,6 @@
 using System.IO.Compression;
 using System.Text;
+using OpenNest.Clamps;
 using OpenNest.Geometry;
 using static OpenNest.IO.Tests.NestArchiveJson;