build(deps): bump react-dom from 19.3.0 to 19.3.1 in /ui

Bumps [react-dom](https://github.com/react/react/tree/HEAD/packages/react-dom) from 19.3.0 to 19.3.1.
- [Release notes](https://github.com/react/react/releases)
- [Changelog](https://github.com/react/react/blob/main/CHANGELOG.md)
- [Commits](https://github.com/react/react/commits/v19.3.1/packages/react-dom)

---
updated-dependencies:
- dependency-name: react-dom
  dependency-version: 19.3.1
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

ui/package-lock.json

@@ -22,7 +22,7 @@
     "@primer/primitives": "^11.10.0",
     "@primer/react": "^38.40.1",
     "react": "^19.3.0",
-    "react-dom": "^19.3.0",
+    "react-dom": "^19.3.1",
     "react-markdown": "^10.1.0",
     "remark-gfm": "^4.0.1",
     "zod": "^4.2.0"