refactor: clean up PlateView after component extraction

Remove dead programIdFont field, unused imports (OpenNest.CNC,
System.ComponentModel, OpenNest.Math, System.Collections.ObjectModel).
PlateView is now 692 lines (down from 1035).

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

OpenNest/Controls/PlateView.cs

@@ -1,5 +1,4 @@
 using OpenNest.Actions;
-using OpenNest.CNC;
 using OpenNest.Collections;
 using OpenNest.Engine.Fill;
 using OpenNest.Forms;
@@ -8,7 +7,6 @@ using OpenNest.Math;
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
-using System.ComponentModel;
 using System.Diagnostics;
 using System.Drawing;
 using System.Drawing.Drawing2D;
@@ -16,14 +14,12 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Windows.Forms;
-using Action = OpenNest.Actions.Action;
 using Timer = System.Timers.Timer;
 
 namespace OpenNest.Controls
 {
     public class PlateView : DrawControl
     {
-        private readonly Font programIdFont;
         private readonly Timer redrawTimer;
 
         private string status;
@@ -89,7 +85,6 @@ namespace OpenNest.Controls
         public PlateView(ColorScheme colorScheme)
         {
             Plate = new Plate(60, 120);
-            programIdFont = new Font(DefaultFont, FontStyle.Bold | FontStyle.Underline);
             origin = new PointF();
             parts = new List<LayoutPart>();
             selection = new SelectionManager(this);
@@ -179,7 +174,6 @@ namespace OpenNest.Controls
             }
         }
 
-
         public double RotateIncrementAngle { get; set; }
 
         public double OffsetIncrementDistance { get; set; }

OpenNest/Controls/SelectionManager.cs

@@ -1,9 +1,7 @@
 using OpenNest.Engine.Fill;
 using OpenNest.Geometry;
-using OpenNest.Math;
 using System;
 using System.Collections.Generic;
-using System.Collections.ObjectModel;
 using System.Drawing;
 using System.Linq;