build(deps): bump react-router from 7.8.1 to 7.12.0 in /shell-ui

Bumps [react-router](https://github.com/remix-run/react-router/tree/HEAD/packages/react-router) from 7.8.1 to 7.12.0.
- [Release notes](https://github.com/remix-run/react-router/releases)
- [Changelog](https://github.com/remix-run/react-router/blob/main/packages/react-router/CHANGELOG.md)
- [Commits](https://github.com/remix-run/react-router/commits/react-router@7.12.0/packages/react-router)

---
updated-dependencies:
- dependency-name: react-router
  dependency-version: 7.12.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]