Stabilize startup and cloud dialog runtime

docs/modernization/tasks.md

@@ -138,6 +138,12 @@ Key facts:
   document export start/branching flows live in
   `src/legacy_document_export_services.*`, and the PPBR dialog opener now lives
   in `src/legacy_brush_package_export_services.*`.
+- The startup/runtime stability slice narrowed several live risks at once: the
+  legacy UI loader again routes XML attributes through virtual node parsers,
+  `NodeComboBox` now guards empty and out-of-range item state, the extracted
+  File-menu binding no longer leaves click callbacks pointing at a dead stack
+  service object, and the cloud-browse dialog now queues file-list/thumbnail UI
+  updates onto the UI thread instead of mutating nodes directly from its worker.
 
 ## Parallel Assignment Rules