fix(studio): pin the drop point on a first resize

The finalize step measures where the committed scale put the box and
shifts the position hold by the difference. Whether the commit had
actually rendered when it measured was luck: on a first resize the
timeline had not re-seeked, so it measured the element at its natural
size still sitting on the drop point, saw no residual, and skipped the
correction. The scale then landed, GSAP rendered it about the element's
centre, and the element jumped by the whole drag distance. Elements
resized before got a correction only because their previous scale made
the residual non-zero by accident.

The committed scale is now applied to the live element before measuring,
so the measurement means what its comment says either way, and a skipped
correction is logged rather than silent.

Confirmed against a real session: a first resize of a 630px chip now
reports residual -109.93 and lands on the drop point, where it previously
logged no scale-finalize at all.

packages/studio/src/utils/elementGsap.ts

@@ -24,6 +24,20 @@ export function setElementGsapPosition(element: HTMLElement, x: number, y: numbe
   return true;
 }
 
+/**
+ * Set the element's GSAP scale. Returns false when no runtime is reachable.
+ *
+ * Used to make the element show a scale that has been committed but not yet
+ * re-rendered by the timeline, so measuring it afterwards reports where the
+ * commit actually puts it rather than where it happened to be mid-flight.
+ */
+export function setElementGsapScale(element: HTMLElement, x: number, y: number): boolean {
+  const gsap = gsapOf(element);
+  if (!gsap?.set) return false;
+  gsap.set(element, { scaleX: x, scaleY: y });
+  return true;
+}
+
 /** The element's GSAP numeric property, or null when unreadable. */
 export function readElementGsapNumber(element: HTMLElement, prop: string): number | null {
   const value = Number(gsapOf(element)?.getProperty?.(element, prop));