feat(ui): add bend line editing to CAD converter

Add Edit link and double-click handler to the bend lines list so
existing bends can be modified without removing and re-adding them.
BendLineDialog gains a LoadBend method to populate fields from an
existing Bend.

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

OpenNest/Controls/FilterPanel.cs

@@ -27,6 +27,7 @@ namespace OpenNest.Controls
         public event EventHandler FilterChanged;
         public event EventHandler<int> BendLineSelected;
         public event EventHandler<int> BendLineRemoved;
+        public event EventHandler<int> BendLineEdited;
         public event EventHandler AddBendLineClicked;
 
         public FilterPanel()
@@ -51,6 +52,18 @@ namespace OpenNest.Controls
             bendLinesList.SelectedIndexChanged += (s, e) =>
                 BendLineSelected?.Invoke(this, bendLinesList.SelectedIndex);
 
+            var bendEditLink = new LinkLabel
+            {
+                Text = "Edit",
+                AutoSize = true,
+                Font = new Font("Segoe UI", 8f)
+            };
+            bendEditLink.LinkClicked += (s, e) =>
+            {
+                if (bendLinesList.SelectedIndex >= 0)
+                    BendLineEdited?.Invoke(this, bendLinesList.SelectedIndex);
+            };
+
             var bendDeleteLink = new LinkLabel
             {
                 Text = "Remove",
@@ -63,6 +76,12 @@ namespace OpenNest.Controls
                     BendLineRemoved?.Invoke(this, bendLinesList.SelectedIndex);
             };
 
+            bendLinesList.DoubleClick += (s, e) =>
+            {
+                if (bendLinesList.SelectedIndex >= 0)
+                    BendLineEdited?.Invoke(this, bendLinesList.SelectedIndex);
+            };
+
             bendAddLink = new LinkLabel
             {
                 Text = "Add Bend Line",
@@ -80,6 +99,7 @@ namespace OpenNest.Controls
                 WrapContents = false
             };
             bendLinksPanel.Controls.Add(bendAddLink);
+            bendLinksPanel.Controls.Add(bendEditLink);
             bendLinksPanel.Controls.Add(bendDeleteLink);
 
             bendLinesPanel.ContentPanel.Controls.Add(bendLinesList);

OpenNest/Forms/BendLineDialog.cs

@@ -99,5 +99,17 @@ namespace OpenNest.Forms
         public double BendAngle => (double)numAngle.Value;
 
         public double? BendRadius => chkRadius.Checked ? (double)numRadius.Value : null;
+
+        public void LoadBend(Bend bend)
+        {
+            cboDirection.SelectedIndex = bend.Direction == BendDirection.Up ? 1 : 0;
+            if (bend.Angle.HasValue)
+                numAngle.Value = (decimal)bend.Angle.Value;
+            if (bend.Radius.HasValue)
+            {
+                chkRadius.Checked = true;
+                numRadius.Value = (decimal)bend.Radius.Value;
+            }
+        }
     }
 }

OpenNest/Forms/CadConverterForm.cs

@@ -41,6 +41,7 @@ namespace OpenNest.Forms
             filterPanel.FilterChanged += OnFilterChanged;
             filterPanel.BendLineSelected += OnBendLineSelected;
             filterPanel.BendLineRemoved += OnBendLineRemoved;
+            filterPanel.BendLineEdited += OnBendLineEdited;
             filterPanel.AddBendLineClicked += OnAddBendLineClicked;
             entityView1.LinePicked += OnLinePicked;
             entityView1.PickCancelled += OnPickCancelled;
@@ -292,6 +293,29 @@ namespace OpenNest.Forms
             entityView1.Invalidate();
         }
 
+        private void OnBendLineEdited(object sender, int index)
+        {
+            var item = CurrentItem;
+            if (item == null || index < 0 || index >= item.Bends.Count) return;
+
+            var bend = item.Bends[index];
+            using var dialog = new BendLineDialog();
+            dialog.LoadBend(bend);
+
+            if (dialog.ShowDialog(this) != DialogResult.OK) return;
+
+            bend.Direction = dialog.Direction;
+            bend.Angle = dialog.BendAngle;
+            bend.Radius = dialog.BendRadius;
+
+            Bend.UpdateEtchEntities(item.Entities, item.Bends);
+            entityView1.Entities.Clear();
+            entityView1.Entities.AddRange(item.Entities);
+            entityView1.Bends = item.Bends;
+            filterPanel.LoadItem(item.Entities, item.Bends);
+            entityView1.Invalidate();
+        }
+
         private void OnQuantityChanged(object sender, EventArgs e)
         {
             var item = CurrentItem;