feat(shapes): add pipe bore, clearance, and blind flag to PipeFlangeShape

Replaces NominalPipeSize (double) with PipeSize (string), PipeClearance (double), and Blind (bool). GetDrawing cuts a center bore at pipeOD + PipeClearance unless Blind is true or PipeSize is unknown/null.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

OpenNest.Core/Shapes/PipeFlangeShape.cs

@@ -5,19 +5,23 @@ namespace OpenNest.Shapes
 {
     public class PipeFlangeShape : ShapeDefinition
     {
-        public double NominalPipeSize { get; set; }
         public double OD { get; set; }
         public double HoleDiameter { get; set; }
         public double HolePatternDiameter { get; set; }
         public int HoleCount { get; set; }
+        public string PipeSize { get; set; }
+        public double PipeClearance { get; set; }
+        public bool Blind { get; set; }
 
         public override void SetPreviewDefaults()
         {
-            NominalPipeSize = 2;
             OD = 7.5;
             HoleDiameter = 0.875;
             HolePatternDiameter = 5.5;
             HoleCount = 8;
+            PipeSize = "2";
+            PipeClearance = 0.0625;
+            Blind = false;
         }
 
         public override Drawing GetDrawing()
@@ -38,6 +42,12 @@ namespace OpenNest.Shapes
                 entities.Add(new Circle(cx, cy, holeRadius));
             }
 
+            if (!Blind && !string.IsNullOrEmpty(PipeSize) && PipeSizes.TryGetOD(PipeSize, out var pipeOD))
+            {
+                var boreDiameter = pipeOD + PipeClearance;
+                entities.Add(new Circle(0, 0, boreDiameter / 2.0));
+            }
+
             return CreateDrawing(entities);
         }
     }

OpenNest.Tests/Shapes/PipeFlangeShapeTests.cs

@@ -29,7 +29,8 @@ public class PipeFlangeShapeTests
             OD = 10,
             HoleDiameter = 1,
             HolePatternDiameter = 7,
-            HoleCount = 4
+            HoleCount = 4,
+            Blind = true
         };
         var drawing = shape.GetDrawing();
 
@@ -51,4 +52,83 @@ public class PipeFlangeShapeTests
 
         Assert.Equal("PipeFlange", drawing.Name);
     }
+
+    [Fact]
+    public void GetDrawing_WithPipeSize_CutsCenterBoreAtPipeODPlusClearance()
+    {
+        var shape = new PipeFlangeShape
+        {
+            OD = 10,
+            HoleDiameter = 1,
+            HolePatternDiameter = 7,
+            HoleCount = 4,
+            PipeSize = "2",       // OD = 2.375
+            PipeClearance = 0.125,
+            Blind = false
+        };
+        var drawing = shape.GetDrawing();
+
+        // Expected bore diameter = 2.375 + 0.125 = 2.5
+        // Area = pi * (5^2 - 0.5^2 * 4 - 1.25^2) = pi * (25 - 1 - 1.5625) = pi * 22.4375
+        var expectedArea = System.Math.PI * 22.4375;
+        Assert.Equal(expectedArea, drawing.Area, 0.5);
+    }
+
+    [Fact]
+    public void GetDrawing_Blind_OmitsCenterBore()
+    {
+        var shape = new PipeFlangeShape
+        {
+            OD = 10,
+            HoleDiameter = 1,
+            HolePatternDiameter = 7,
+            HoleCount = 4,
+            PipeSize = "2",
+            PipeClearance = 0.125,
+            Blind = true
+        };
+        var drawing = shape.GetDrawing();
+
+        // With Blind=true, area = outer - 4 bolt holes = pi * (25 - 1) = pi * 24
+        var expectedArea = System.Math.PI * 24;
+        Assert.Equal(expectedArea, drawing.Area, 0.5);
+    }
+
+    [Fact]
+    public void GetDrawing_UnknownPipeSize_OmitsCenterBore()
+    {
+        var shape = new PipeFlangeShape
+        {
+            OD = 10,
+            HoleDiameter = 1,
+            HolePatternDiameter = 7,
+            HoleCount = 4,
+            PipeSize = "not-a-real-pipe",
+            PipeClearance = 0.125,
+            Blind = false
+        };
+        var drawing = shape.GetDrawing();
+
+        // Unknown pipe size → no bore, area matches blind case
+        var expectedArea = System.Math.PI * 24;
+        Assert.Equal(expectedArea, drawing.Area, 0.5);
+    }
+
+    [Fact]
+    public void GetDrawing_NullOrEmptyPipeSize_OmitsCenterBore()
+    {
+        var shape = new PipeFlangeShape
+        {
+            OD = 10,
+            HoleDiameter = 1,
+            HolePatternDiameter = 7,
+            HoleCount = 4,
+            PipeSize = null,
+            PipeClearance = 0.125
+        };
+        var drawing = shape.GetDrawing();
+
+        var expectedArea = System.Math.PI * 24;
+        Assert.Equal(expectedArea, drawing.Area, 0.5);
+    }
 }