chore(deps): bump next from 15.5.12 to 15.5.15 in /website

Bumps [next](https://github.com/vercel/next.js) from 15.5.12 to 15.5.15.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.5.12...v15.5.15)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.5.15
  dependency-type: direct:production
...

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

Author: dependabot[bot]

website/package-lock.json

@@ -14,7 +14,7 @@
     "clsx": "^2.1.1",
     "lucide-react": "^0.475.0",
     "motion": "^12.37.0",
-    "next": "^15.3.0",
+    "next": "^15.5.15",
     "next-themes": "^0.4.6",
     "react": "^19.0.0",
     "react-dom": "^19.0.0",