feat: regenerate cut-offs after part drag and fill operations

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

OpenNest/Actions/ActionClone.cs

@@ -167,6 +167,9 @@ namespace OpenNest.Actions
             }
 
             parts.ForEach(p => plateView.Plate.Parts.Add(p.BasePart.Clone() as Part));
+
+            if (plateView.Plate.CutOffs.Count > 0)
+                plateView.Plate.RegenerateCutOffs(plateView.CutOffSettings);
         }
 
         private void Fill()

OpenNest/Actions/ActionSelect.cs

@@ -133,6 +133,12 @@ namespace OpenNest.Actions
                 plateView.Invalidate();
                 status = Status.SetFirstPoint;
             }
+            else if (plateView.SelectedParts.Count > 0)
+            {
+                // Part drag completed — regenerate cut-off programs
+                if (plateView.Plate.CutOffs.Count > 0)
+                    plateView.Plate.RegenerateCutOffs(plateView.CutOffSettings);
+            }
         }
 
         private void plateView_Paint(object sender, PaintEventArgs e)

OpenNest/Controls/PlateView.cs

@@ -1089,6 +1089,10 @@ namespace OpenNest.Controls
                 if (parts.Count > 0 && (!cts.IsCancellationRequested || progressForm.Accepted))
                 {
                     AcceptPreviewParts(parts);
+
+                    if (Plate.CutOffs.Count > 0)
+                        Plate.RegenerateCutOffs(cutOffSettings);
+
                     sw.Stop();
                     Status = $"Fill: {parts.Count} parts in {sw.ElapsedMilliseconds} ms";
                 }