chore: Bump stylelint-config-standard from 39.0.1 to 40.0.0 in /frontend

Bumps [stylelint-config-standard](https://github.com/stylelint/stylelint-config-standard) from 39.0.1 to 40.0.0.
- [Release notes](https://github.com/stylelint/stylelint-config-standard/releases)
- [Changelog](https://github.com/stylelint/stylelint-config-standard/blob/main/CHANGELOG.md)
- [Commits](stylelint/stylelint-config-standard@39.0.1...40.0.0)

---
updated-dependencies:
- dependency-name: stylelint-config-standard
  dependency-version: 40.0.0
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

frontend/package-lock.json

@@ -40,7 +40,7 @@
     "postcss-html": "^1.8.1",
     "stylelint": "^16.26.1",
     "stylelint-config-recommended-vue": "^1.6.1",
-    "stylelint-config-standard": "^39.0.1",
+    "stylelint-config-standard": "^40.0.0",
     "vite": "^7.3.1",
     "vite-plugin-vuetify": "^2.1.2",
     "vitest": "^4.0.15",