build(deps): bump react-router from 7.9.3 to 7.15.0 in /frontend

Bumps [react-router](https://github.com/remix-run/react-router/tree/HEAD/packages/react-router) from 7.9.3 to 7.15.0.
- [Release notes](https://github.com/remix-run/react-router/releases)
- [Changelog](https://github.com/remix-run/react-router/blob/main/packages/react-router/CHANGELOG.md)
- [Commits](https://github.com/remix-run/react-router/commits/react-router@7.15.0/packages/react-router)

---
updated-dependencies:
- dependency-name: react-router
  dependency-version: 7.15.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

frontend/package-lock.json

@@ -27,7 +27,7 @@
     "react": "^19.1.1",
     "react-dom": "^19.1.1",
     "react-i18next": "^16.1.0",
-    "react-router": "^7.9.2",
+    "react-router": "^7.15.0",
     "recharts": "^3.3.0"
   },
   "devDependencies": {