Fix ReactDOM.render usage (#1267)

## Summary
- render popups with createRoot
- document the fix in CHANGELOG

## Testing
- `npm run lint`
- `npm run build`
- `apt run xvfb` *(fails: Invalid operation)*
- `xvfb-run -a npm run test` *(fails: command not found)*

------
https://chatgpt.com/codex/tasks/task_e_686915f46ba883319b83639b6b71cc6b

CHANGELOG.md

@@ -23,6 +23,8 @@
 
 - Fix incorrect handing of network error response (#944)
 - Show an error when adding a layer with a duplicate ID
+- Replace deprecated `ReactDOM.render` usage with `createRoot` and drop the
+  `DOMNodeRemoved` cleanup hack
 - _...Add new stuff here..._
 
 ## 2.1.1