chore(Hi.WinForm): follow the DispEngine FrameReady callback (was ImageRequestAfterBufferSwapped)

Mechanical: the handler gains the FramePins argument and ignores it; this
host is deprecated and gets no pin overlay.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Disp/RenderingCanvas.cs

@@ -94,7 +94,7 @@ namespace Hi.WinForm.Disp
             DispEngine.BackgroundColor = new Vec3d(0.1, 0.1, 0.5);
             DispEngine.BackgroundOpacity = 0.1;
             DispEngine.SetViewToHomeView();
-            DispEngine.ImageRequestAfterBufferSwapped += DispEngine_ImageRequestAfterBufferSwapped;
+            DispEngine.FrameReady += DispEngine_FrameReady;
 
             // Set initial size and start the rendering engine
             this.Size = new System.Drawing.Size(500, 300);
@@ -185,7 +185,7 @@ namespace Hi.WinForm.Disp
         #endregion
 
         #region DispEngine_Rendering
-        private unsafe void DispEngine_ImageRequestAfterBufferSwapped(byte* bgra_unsignedbyte_pixels, int w, int h)
+        private unsafe void DispEngine_FrameReady(byte* bgra_unsignedbyte_pixels, int w, int h, FramePins pins)
         {
             // Create a bitmap from the raw pixel data provided by DispEngine
             Bitmap bitmap;