chore(deps-dev): Bump esbuild from 0.25.6 to 0.25.9 in /backend

Bumps [esbuild](https://github.com/evanw/esbuild) from 0.25.6 to 0.25.9.
- [Release notes](https://github.com/evanw/esbuild/releases)
- [Changelog](https://github.com/evanw/esbuild/blob/main/CHANGELOG.md)
- [Commits](evanw/esbuild@v0.25.6...v0.25.9)

---
updated-dependencies:
- dependency-name: esbuild
  dependency-version: 0.25.9
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]