feat: add auto-tab size range fields to CuttingParameters

Add AutoTabMinSize and AutoTabMaxSize properties to enable automatic tab
assignment based on part size. Update CuttingParametersSerializer for
round-trip serialization and add tests.

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

OpenNest.Tests/CuttingStrategy/CuttingParametersSerializerTests.cs

@@ -0,0 +1,35 @@
+using OpenNest.CNC.CuttingStrategy;
+using OpenNest.Forms;
+
+namespace OpenNest.Tests.CuttingStrategy;
+
+public class CuttingParametersSerializerTests
+{
+    [Fact]
+    public void RoundTrip_PreservesAutoTabFields()
+    {
+        var original = new CuttingParameters
+        {
+            AutoTabMinSize = 0.5,
+            AutoTabMaxSize = 3.0,
+            ExternalLeadIn = new LineLeadIn { Length = 0.25, ApproachAngle = 90 }
+        };
+
+        var json = CuttingParametersSerializer.Serialize(original);
+        var restored = CuttingParametersSerializer.Deserialize(json);
+
+        Assert.Equal(0.5, restored.AutoTabMinSize);
+        Assert.Equal(3.0, restored.AutoTabMaxSize);
+    }
+
+    [Fact]
+    public void Deserialize_MissingAutoTabFields_DefaultsToZero()
+    {
+        var json = "{\"externalLeadIn\":{\"type\":\"None\"},\"externalLeadOut\":{\"type\":\"None\"},\"internalLeadIn\":{\"type\":\"None\"},\"internalLeadOut\":{\"type\":\"None\"},\"arcCircleLeadIn\":{\"type\":\"None\"},\"arcCircleLeadOut\":{\"type\":\"None\"},\"tabsEnabled\":false,\"tabWidth\":0.25,\"pierceClearance\":0.0625}";
+
+        var restored = CuttingParametersSerializer.Deserialize(json);
+
+        Assert.Equal(0.0, restored.AutoTabMinSize);
+        Assert.Equal(0.0, restored.AutoTabMaxSize);
+    }
+}