Bump fumadocs-ui from 15.8.5 to 16.0.4 in /docs

Bumps [fumadocs-ui](https://github.com/fuma-nama/fumadocs) from 15.8.5 to 16.0.4.
- [Release notes](https://github.com/fuma-nama/fumadocs/releases)
- [Commits](https://github.com/fuma-nama/fumadocs/commits/fumadocs-ui@16.0.4)

---
updated-dependencies:
- dependency-name: fumadocs-ui
  dependency-version: 16.0.4
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

docs/package-lock.json

@@ -12,7 +12,7 @@
     "fumadocs-core": "^15.8.5",
     "fumadocs-mdx": "^12.0.3",
     "fumadocs-typescript": "^4.0.11",
-    "fumadocs-ui": "^15.8.5",
+    "fumadocs-ui": "^16.0.4",
     "next": "^15.5.6",
     "react": "^19.0.0",
     "react-dom": "^19.2.0"