fix(renderer): derive backing size from viewport state

view/CanvasViewport.tsx

@@ -17,8 +17,6 @@ export function CanvasViewport({ store }: CanvasViewportProps) {
 
       const width = Math.floor(entry.contentRect.width);
       const height = Math.floor(entry.contentRect.height);
-      canvas.width = width;
-      canvas.height = height;
       store.dispatch("viewport.setSize", { w: width, h: height });
     });