Bump vitest from 2.1.8 to 2.1.9 in /frontend

Bumps [vitest](https://github.com/vitest-dev/vitest/tree/HEAD/packages/vitest) from 2.1.8 to 2.1.9.
- [Release notes](https://github.com/vitest-dev/vitest/releases)
- [Commits](https://github.com/vitest-dev/vitest/commits/v2.1.9/packages/vitest)

---
updated-dependencies:
- dependency-name: vitest
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

frontend/package-lock.json

@@ -92,6 +92,6 @@
     "typescript": "5.7.2",
     "typescript-eslint": "8.19.1",
     "vite": "6.0.7",
-    "vitest": "2.1.8"
+    "vitest": "2.1.9"
   }
 }