fix: improve fill progress reporting and engine pipeline

- Strategies now promote results to IsOverallBest when they beat the
  pipeline best, so the UI updates immediately on improvement rather
  than waiting for each phase to complete
- PlateView only updates the main view on overall-best results, fixing
  intermediate angle-sweep layouts leaking to the plate display
- Skip Row/Column strategies for rectangle parts (redundant with Linear)
- Intercept Escape key at MainForm level via ProcessCmdKey so it always
  reaches the active PlateView regardless of focus state
- Restore keyboard focus to PlateView after fill progress form closes
- Remnant engines use SelectBestFitPair for orientation-aware pair
  selection; DefaultNestEngine tries both landscape and portrait pairs
- RemnantFiller preserves more parts during topmost-part removal

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

OpenNest/Controls/PlateView.cs

@@ -412,6 +412,16 @@ namespace OpenNest.Controls
             }
         }
 
+        public void ProcessEscapeKey()
+        {
+            if (currentAction.IsBusy())
+                currentAction.CancelAction();
+            else if (currentAction is ActionSelect && previousAction != null)
+                RestorePreviousAction();
+            else
+                SetAction(typeof(ActionSelect));
+        }
+
         protected override bool ProcessDialogKey(Keys keyData)
         {
             // Only handle TAB, RETURN, ESC, and ARROW KEYS here.
@@ -420,12 +430,7 @@ namespace OpenNest.Controls
             switch (keyData)
             {
                 case Keys.Escape:
-                    if (currentAction.IsBusy())
-                        currentAction.CancelAction();
-                    else if (currentAction is ActionSelect && previousAction != null)
-                        RestorePreviousAction();
-                    else
-                        SetAction(typeof(ActionSelect));
+                    ProcessEscapeKey();
                     break;
 
                 case Keys.Left:
@@ -791,9 +796,11 @@ namespace OpenNest.Controls
                 progressForm.UpdateProgress(p);
 
                 if (p.IsOverallBest)
+                {
                     progressForm.UpdatePreview(p.BestParts);
+                    SetActiveParts(p.BestParts);
+                }
 
-                SetActiveParts(p.BestParts);
                 ActiveWorkArea = p.ActiveWorkArea;
             });
 
@@ -837,6 +844,7 @@ namespace OpenNest.Controls
                 ActiveWorkArea = null;
                 progressForm.Close();
                 cts.Dispose();
+                Focus();
             }
         }
 

OpenNest/Forms/MainForm.cs

@@ -29,6 +29,17 @@ namespace OpenNest.Forms
         private const float ZoomInFactor = 1.5f;
         private const float ZoomOutFactor = 1.0f / ZoomInFactor;
 
+        protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
+        {
+            if (keyData == Keys.Escape && activeForm?.PlateView != null)
+            {
+                activeForm.PlateView.ProcessEscapeKey();
+                return true;
+            }
+
+            return base.ProcessCmdKey(ref msg, keyData);
+        }
+
         public MainForm()
         {
             InitializeComponent();