Fix I-2: dangling parent on shell/ColumnLayout-rooted AI-replace trees

treeToCraftState's ROOT re-key branch reparented nodes['ROOT'].nodes
children to 'ROOT' but not nodes['ROOT'].linkedNodes children. For a
ColumnLayout- or Section/BackgroundSection/FormContainer-rooted AI
`replace`, flattenTreeForCraft puts content in linkedNodes (col-N /
section-inner etc.) whose parent was left pointing at the OLD root id
-- which is then deleted, leaving a dangling parent reference that
breaks select/move/delete of those nodes in the Craft.js editor.

Now the same loop that reparents nodes[] children also reparents
linkedNodes children.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

craft/src/state/PageContext.tsx

@@ -86,6 +86,16 @@ export function treeToCraftState(tree: SerializedTreeNode): string {
     for (const childId of nodes['ROOT'].nodes) {
       if (nodes[childId]) nodes[childId].parent = 'ROOT';
     }
+    // I-2: linkedNodes children (e.g. ColumnLayout's col-0/col-1, or a
+    // Section/BackgroundSection/FormContainer's SHELL_INNER wrapper) need
+    // the same reparenting as nodes[] children above. Without this, a
+    // ColumnLayout/SHELL_INNER-rooted AI `replace` leaves those children's
+    // `parent` pointing at the OLD root id, which is then `delete`d --
+    // producing a dangling parent reference that breaks select/move/delete
+    // of those nodes in the Craft.js editor.
+    for (const linkedId of Object.values(nodes['ROOT'].linkedNodes)) {
+      if (nodes[linkedId]) nodes[linkedId].parent = 'ROOT';
+    }
   }
   return JSON.stringify(nodes);
 }