Bump postcss from 8.4.35 to 8.5.10 in /frontend

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.35 to 8.5.10.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.35...8.5.10)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.10
  dependency-type: direct:development
...

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

Author: dependabot[bot]

frontend/package-lock.json

@@ -49,7 +49,7 @@
     "globals": "^16.5.0",
     "happy-dom": "^20.8.9",
     "jsdom": "^27.2.0",
-    "postcss": "^8.4.35",
+    "postcss": "^8.5.10",
     "tailwindcss": "^3.4.1",
     "typescript": "~5.9.3",
     "typescript-eslint": "^8.46.3",