Bump @vitest/coverage-v8 from 2.1.9 to 4.0.18 in /frontend

Bumps [@vitest/coverage-v8](https://github.com/vitest-dev/vitest/tree/HEAD/packages/coverage-v8) from 2.1.9 to 4.0.18.
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v4.0.18/packages/coverage-v8)

---
updated-dependencies:
- dependency-name: "@vitest/coverage-v8"
  dependency-version: 4.0.18
  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

@@ -30,7 +30,7 @@
     "@tailwindcss/vite": "^4.1.18",
     "@types/node": "^22.10.0",
     "@typescript-eslint/parser": "^8.0.0",
-    "@vitest/coverage-v8": "^2.1.0",
+    "@vitest/coverage-v8": "^4.0.18",
     "@vitejs/plugin-vue": "^5.2.0",
     "@vue/test-utils": "^2.4.6",
     "autoprefixer": "^10.4.20",