refactor: organize test project into subdirectories by feature area

Move 43 root-level test files into feature-specific subdirectories
mirroring the main codebase structure: Geometry, Fill, BestFit, CutOffs,
CuttingStrategy, Engine, IO. Update namespaces to match folder paths.

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

OpenNest.Tests/CuttingStrategy/CuttingResultTests.cs

@@ -0,0 +1,22 @@
+using OpenNest.CNC;
+using OpenNest.CNC.CuttingStrategy;
+using OpenNest.Geometry;
+
+namespace OpenNest.Tests.CuttingStrategy;
+
+public class CuttingResultTests
+{
+    [Fact]
+    public void CuttingResult_StoresValues()
+    {
+        var pgm = new Program();
+        pgm.Codes.Add(new RapidMove(new Vector(1, 2)));
+        var point = new Vector(3, 4);
+
+        var result = new CuttingResult { Program = pgm, LastCutPoint = point };
+
+        Assert.Same(pgm, result.Program);
+        Assert.Equal(3, result.LastCutPoint.X);
+        Assert.Equal(4, result.LastCutPoint.Y);
+    }
+}