feat: add F key shortcut for zoom-to-fit on EntityView

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

OpenNest/Controls/EntityView.cs

@@ -117,6 +117,14 @@ namespace OpenNest.Controls
                 ZoomToFit();
         }
 
+        protected override void OnKeyDown(KeyEventArgs e)
+        {
+            base.OnKeyDown(e);
+
+            if (e.KeyCode == Keys.F)
+                ZoomToFit();
+        }
+
         private Pen GetEntityPen(Color color)
         {
             if (color.IsEmpty || color.A == 0)