chore(deps): bump tailwindcss from 3.4.19 to 4.2.0 in /frontend

Bumps [tailwindcss](https://github.com/tailwindlabs/tailwindcss/tree/HEAD/packages/tailwindcss) from 3.4.19 to 4.2.0.
- [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/v4.2.0/packages/tailwindcss)

---
updated-dependencies:
- dependency-name: tailwindcss
  dependency-version: 4.2.0
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

frontend/package.json

@@ -62,7 +62,7 @@
     "autoprefixer": "^10.4.16",
     "happy-dom": "^20.7.0",
     "postcss": "^8.4.32",
-    "tailwindcss": "^3.4.0",
+    "tailwindcss": "^4.2.1",
     "typescript": "^5.9.3",
     "vite": "^6.4.1",
     "vitest": "^4.0.18",