feat(core): add IsoscelesTriangleShape

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

OpenNest.Core/Shapes/IsoscelesTriangleShape.cs

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+using System.Collections.Generic;
+using OpenNest.Geometry;
+
+namespace OpenNest.Shapes
+{
+    public class IsoscelesTriangleShape : ShapeDefinition
+    {
+        public double Base { get; set; }
+        public double Height { get; set; }
+
+        public override Drawing GetDrawing()
+        {
+            var midX = Base / 2.0;
+
+            var entities = new List<Entity>
+            {
+                new Line(0, 0, Base, 0),
+                new Line(Base, 0, midX, Height),
+                new Line(midX, Height, 0, 0)
+            };
+
+            return CreateDrawing(entities);
+        }
+    }
+}

OpenNest.Core/Shapes/LShape.cs

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+using System.Collections.Generic;
+using OpenNest.Geometry;
+
+namespace OpenNest.Shapes
+{
+    public class LShape : ShapeDefinition
+    {
+        public double Width { get; set; }
+        public double Height { get; set; }
+        public double LegWidth { get; set; }
+        public double LegHeight { get; set; }
+
+        public override Drawing GetDrawing()
+        {
+            var lw = LegWidth > 0 ? LegWidth : Width / 2.0;
+            var lh = LegHeight > 0 ? LegHeight : Height / 2.0;
+
+            var entities = new List<Entity>
+            {
+                new Line(0, 0, Width, 0),
+                new Line(Width, 0, Width, lh),
+                new Line(Width, lh, lw, lh),
+                new Line(lw, lh, lw, Height),
+                new Line(lw, Height, 0, Height),
+                new Line(0, Height, 0, 0)
+            };
+
+            return CreateDrawing(entities);
+        }
+    }
+}

OpenNest.Tests/Shapes/IsoscelesTriangleShapeTests.cs

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+using OpenNest.Shapes;
+
+namespace OpenNest.Tests.Shapes;
+
+public class IsoscelesTriangleShapeTests
+{
+    [Fact]
+    public void GetDrawing_BoundingBoxMatchesDimensions()
+    {
+        var shape = new IsoscelesTriangleShape { Base = 10, Height = 8 };
+        var drawing = shape.GetDrawing();
+
+        var bbox = drawing.Program.BoundingBox();
+        Assert.Equal(10, bbox.Width, 0.01);
+        Assert.Equal(8, bbox.Length, 0.01);
+    }
+
+    [Fact]
+    public void GetDrawing_AreaIsHalfBaseTimesHeight()
+    {
+        var shape = new IsoscelesTriangleShape { Base = 10, Height = 8 };
+        var drawing = shape.GetDrawing();
+
+        Assert.Equal(40, drawing.Area, 0.5);
+    }
+}

OpenNest.Tests/Shapes/LShapeTests.cs

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+using OpenNest.Shapes;
+
+namespace OpenNest.Tests.Shapes;
+
+public class LShapeTests
+{
+    [Fact]
+    public void GetDrawing_BoundingBoxMatchesDimensions()
+    {
+        var shape = new LShape { Width = 10, Height = 20 };
+        var drawing = shape.GetDrawing();
+
+        var bbox = drawing.Program.BoundingBox();
+        Assert.Equal(10, bbox.Width, 0.01);
+        Assert.Equal(20, bbox.Length, 0.01);
+    }
+
+    [Fact]
+    public void GetDrawing_DefaultLegDimensions()
+    {
+        var shape = new LShape { Width = 10, Height = 20 };
+        var drawing = shape.GetDrawing();
+
+        // Default legs: LegWidth = Width/2 = 5, LegHeight = Height/2 = 10
+        // Area = Width*Height - (Width - LegWidth) * (Height - LegHeight)
+        // Area = 10*20 - 5*10 = 150
+        Assert.Equal(150, drawing.Area, 0.5);
+    }
+
+    [Fact]
+    public void GetDrawing_CustomLegDimensions()
+    {
+        var shape = new LShape { Width = 10, Height = 20, LegWidth = 3, LegHeight = 5 };
+        var drawing = shape.GetDrawing();
+
+        // Area = Width*Height - (Width - LegWidth) * (Height - LegHeight)
+        // Area = 10*20 - 7*15 = 200 - 105 = 95
+        Assert.Equal(95, drawing.Area, 0.5);
+    }
+}