fix(deps): bump @tailwindcss/vite from 4.1.11 to 4.2.1 in /frontend

Bumps [@tailwindcss/vite](https://github.com/tailwindlabs/tailwindcss/tree/HEAD/packages/@tailwindcss-vite) from 4.1.11 to 4.2.1.
- [Release notes](https://github.com/tailwindlabs/tailwindcss/releases)
- [Changelog](https://github.com/tailwindlabs/tailwindcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/tailwindlabs/tailwindcss/commits/v4.2.1/packages/@tailwindcss-vite)

---
updated-dependencies:
- dependency-name: "@tailwindcss/vite"
  dependency-version: 4.2.1
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]