fix(studio): bake the group transform into members on ungroup (#1764)

Ungroup only baked the wrapper's layout (left/top), not its GSAP transform — so a
moved group's members snapped back to their creation-time positions. Distribute the
group's static transform onto each member before stripping it: translation is an
exact per-axis add; rotation/scale are composed about the group center so off-center
members don't drift. Animated group transforms are left to be stripped, not baked.

packages/studio-server/src/helpers/sourceMutation.ts

@@ -404,6 +404,15 @@ export interface WrapElementsResult {
 export interface UnwrapElementsResult {
   html: string;
   unwrapped: boolean;
+  /** The unwrapped wrapper's id, so callers can strip GSAP that targeted it
+   *  (the wrapper is gone; a leftover `gsap.set("#id")` would throw at runtime). */
+  unwrappedGroupId?: string;
+  /** Members (id'd children) with their absolute layout centres (post un-rebase),
+   *  so the caller can BAKE the group's GSAP transform into each member before
+   *  stripping it — otherwise the group's moves are lost on ungroup. */
+  members?: Array<{ id: string; cx: number; cy: number }>;
+  /** The wrapper's layout centre — the pivot for baking the group's rotation/scale. */
+  groupCenter?: { cx: number; cy: number };
 }
 
 export interface ElementRebase {
@@ -554,22 +563,36 @@ export function unwrapElementsFromHtml(
   // Undo the rebase: child absolute position = child (rebased) + wrapper origin.
   const wLeft = getInlineStylePx(group, "left");
   const wTop = getInlineStylePx(group, "top");
+  const groupCenter = {
+    cx: wLeft + getInlineStylePx(group, "width") / 2,
+    cy: wTop + getInlineStylePx(group, "height") / 2,
+  };
 
   // Move children back to the wrapper's slot, preserving order.
+  const members: Array<{ id: string; cx: number; cy: number }> = [];
   for (const child of Array.from(group.children)) {
     if (isHTMLElement(child)) {
-      setInlineLeftTop(
-        child,
-        getInlineStylePx(child, "left") + wLeft,
-        getInlineStylePx(child, "top") + wTop,
-      );
+      const newLeft = getInlineStylePx(child, "left") + wLeft;
+      const newTop = getInlineStylePx(child, "top") + wTop;
+      setInlineLeftTop(child, newLeft, newTop);
+      if (child.id) {
+        members.push({
+          id: child.id,
+          cx: newLeft + getInlineStylePx(child, "width") / 2,
+          cy: newTop + getInlineStylePx(child, "height") / 2,
+        });
+      }
     }
     parent.insertBefore(child, group);
   }
+  const groupId = group.id || undefined;
   group.remove();
 
   return {
     html: wrappedFragment ? document.body.innerHTML || "" : document.toString(),
     unwrapped: true,
+    unwrappedGroupId: groupId,
+    members,
+    groupCenter,
   };
 }