Bump esbuild from 0.25.6 to 0.28.1 in /xref-helper (#679)

Bumps [esbuild](https://github.com/evanw/esbuild) from 0.25.6 to 0.28.1.
- [Release notes](https://github.com/evanw/esbuild/releases)
- [Changelog](https://github.com/evanw/esbuild/blob/main/CHANGELOG-2025.md)
- [Commits](evanw/esbuild@v0.25.6...v0.28.1)

---
updated-dependencies:
- dependency-name: esbuild
  dependency-version: 0.28.1
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]