feat: integrate geometry simplifier into CadConverterForm

Add "Simplify..." button to the detail bar and wire up SimplifierViewerForm
as a tool window with lazy creation, positioning, and entity replacement on apply.

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

OpenNest/Forms/CadConverterForm.Designer.cs

@@ -28,6 +28,7 @@ namespace OpenNest.Forms
             lblDimensions = new System.Windows.Forms.Label();
             lblEntityCount = new System.Windows.Forms.Label();
             btnSplit = new System.Windows.Forms.Button();
+            btnSimplify = new System.Windows.Forms.Button();
             lblDetect = new System.Windows.Forms.Label();
             cboBendDetector = new System.Windows.Forms.ComboBox();
             bottomPanel1 = new OpenNest.Controls.BottomPanel();
@@ -127,6 +128,7 @@ namespace OpenNest.Forms
             detailBar.Controls.Add(lblDimensions);
             detailBar.Controls.Add(lblEntityCount);
             detailBar.Controls.Add(btnSplit);
+            detailBar.Controls.Add(btnSimplify);
             detailBar.Controls.Add(lblDetect);
             detailBar.Controls.Add(cboBendDetector);
             detailBar.Dock = System.Windows.Forms.DockStyle.Bottom;
@@ -214,6 +216,15 @@ namespace OpenNest.Forms
             btnSplit.TabIndex = 6;
             btnSplit.Text = "Split...";
             //
+            // btnSimplify
+            //
+            btnSimplify.FlatStyle = System.Windows.Forms.FlatStyle.Flat;
+            btnSimplify.Font = new System.Drawing.Font("Segoe UI", 9F);
+            btnSimplify.Text = "Simplify...";
+            btnSimplify.AutoSize = true;
+            btnSimplify.Margin = new System.Windows.Forms.Padding(4, 0, 0, 0);
+            btnSimplify.Click += new System.EventHandler(this.OnSimplifyClick);
+            //
             // lblDetect
             //
             lblDetect.AutoSize = true;
@@ -312,6 +323,7 @@ namespace OpenNest.Forms
         private System.Windows.Forms.NumericUpDown numQuantity;
         private System.Windows.Forms.TextBox txtCustomer;
         private System.Windows.Forms.Button btnSplit;
+        private System.Windows.Forms.Button btnSimplify;
         private System.Windows.Forms.ComboBox cboBendDetector;
         private System.Windows.Forms.Label lblQty;
         private System.Windows.Forms.Label lblCust;

OpenNest/Forms/CadConverterForm.cs

@@ -20,6 +20,7 @@ namespace OpenNest.Forms
     public partial class CadConverterForm : Form
     {
         private static int colorIndex;
+        private SimplifierViewerForm simplifierViewer;
 
         public CadConverterForm()
         {
@@ -378,6 +379,42 @@ namespace OpenNest.Forms
             }
         }
 
+        private void OnSimplifyClick(object sender, EventArgs e)
+        {
+            if (entityView1.Entities == null || entityView1.Entities.Count == 0)
+                return;
+
+            var shapes = ShapeBuilder.GetShapes(entityView1.Entities);
+            if (shapes.Count == 0)
+                return;
+
+            if (simplifierViewer == null || simplifierViewer.IsDisposed)
+            {
+                simplifierViewer = new SimplifierViewerForm();
+                simplifierViewer.Owner = this;
+                simplifierViewer.Applied += OnSimplifierApplied;
+
+                // Position next to this form
+                var screen = Screen.FromControl(this);
+                simplifierViewer.Location = new Point(
+                    System.Math.Min(Right, screen.WorkingArea.Right - simplifierViewer.Width),
+                    Top);
+            }
+
+            simplifierViewer.LoadShapes(shapes, entityView1);
+        }
+
+        private void OnSimplifierApplied(List<Entity> entities)
+        {
+            entityView1.Entities.Clear();
+            entityView1.Entities.AddRange(entities);
+            entityView1.ZoomToFit();
+            entityView1.Invalidate();
+
+            // Update entity count label
+            lblEntityCount.Text = $"{entities.Count} entities";
+        }
+
         #endregion
 
         #region Output