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/Engine/PlateProcessorTests.cs

@@ -0,0 +1,127 @@
+using OpenNest.CNC.CuttingStrategy;
+using OpenNest.Engine;
+using OpenNest.Engine.RapidPlanning;
+using OpenNest.Engine.Sequencing;
+
+namespace OpenNest.Tests.Engine;
+
+public class PlateProcessorTests
+{
+    private static Part MakePartAt(double x, double y) => TestHelpers.MakePartAt(x, y, size: 2);
+
+    [Fact]
+    public void Process_ReturnsAllParts()
+    {
+        var plate = new Plate(60, 120);
+        plate.Parts.Add(MakePartAt(10, 10));
+        plate.Parts.Add(MakePartAt(30, 30));
+        plate.Parts.Add(MakePartAt(50, 50));
+
+        var processor = new PlateProcessor
+        {
+            Sequencer = new RightSideSequencer(),
+            RapidPlanner = new SafeHeightRapidPlanner()
+        };
+
+        var result = processor.Process(plate);
+
+        Assert.Equal(3, result.Parts.Count);
+    }
+
+    [Fact]
+    public void Process_PreservesSequenceOrder()
+    {
+        var plate = new Plate(60, 120);
+        var left = MakePartAt(5, 10);
+        var right = MakePartAt(50, 10);
+        plate.Parts.Add(left);
+        plate.Parts.Add(right);
+
+        var processor = new PlateProcessor
+        {
+            Sequencer = new RightSideSequencer(),
+            RapidPlanner = new SafeHeightRapidPlanner()
+        };
+
+        var result = processor.Process(plate);
+
+        Assert.Same(right, result.Parts[0].Part);
+        Assert.Same(left, result.Parts[1].Part);
+    }
+
+    [Fact]
+    public void Process_SkipsCuttingStrategy_WhenManualLeadIns()
+    {
+        var plate = new Plate(60, 120);
+        var part = MakePartAt(10, 10);
+        part.HasManualLeadIns = true;
+        plate.Parts.Add(part);
+
+        var processor = new PlateProcessor
+        {
+            Sequencer = new LeftSideSequencer(),
+            CuttingStrategy = new ContourCuttingStrategy
+            {
+                Parameters = new CuttingParameters()
+            },
+            RapidPlanner = new SafeHeightRapidPlanner()
+        };
+
+        var result = processor.Process(plate);
+
+        Assert.Same(part.Program, result.Parts[0].ProcessedProgram);
+    }
+
+    [Fact]
+    public void Process_DoesNotMutatePart()
+    {
+        var plate = new Plate(60, 120);
+        var part = MakePartAt(10, 10);
+        var originalProgram = part.Program;
+        plate.Parts.Add(part);
+
+        var processor = new PlateProcessor
+        {
+            Sequencer = new LeftSideSequencer(),
+            RapidPlanner = new SafeHeightRapidPlanner()
+        };
+
+        var result = processor.Process(plate);
+
+        Assert.Same(originalProgram, part.Program);
+    }
+
+    [Fact]
+    public void Process_NoCuttingStrategy_PassesProgramThrough()
+    {
+        var plate = new Plate(60, 120);
+        var part = MakePartAt(10, 10);
+        plate.Parts.Add(part);
+
+        var processor = new PlateProcessor
+        {
+            Sequencer = new LeftSideSequencer(),
+            RapidPlanner = new SafeHeightRapidPlanner()
+        };
+
+        var result = processor.Process(plate);
+
+        Assert.Same(part.Program, result.Parts[0].ProcessedProgram);
+    }
+
+    [Fact]
+    public void Process_EmptyPlate_ReturnsEmptyResult()
+    {
+        var plate = new Plate(60, 120);
+
+        var processor = new PlateProcessor
+        {
+            Sequencer = new LeftSideSequencer(),
+            RapidPlanner = new SafeHeightRapidPlanner()
+        };
+
+        var result = processor.Process(plate);
+
+        Assert.Empty(result.Parts);
+    }
+}