Bump webpack from 5.98.0 to 5.99.9 in /frontend

Bumps [webpack](https://github.com/webpack/webpack) from 5.98.0 to 5.99.9.
- [Release notes](https://github.com/webpack/webpack/releases)
- [Commits](https://github.com/webpack/webpack/compare/v5.98.0...v5.99.9)

---
updated-dependencies:
- dependency-name: webpack
  dependency-version: 5.99.9
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

frontend/sync-client/package.json

@@ -29,7 +29,7 @@
         "ts-loader": "^9.5.2",
         "tslib": "2.8.1",
         "typescript": "5.8.3",
-        "webpack": "^5.98.0",
+        "webpack": "^5.99.9",
         "webpack-cli": "^6.0.1",
         "webpack-merge": "^6.0.1",
         "ws": "^8.18.2"