Bump next from 15.3.3 to 15.4.7 in /demo

Bumps [next](https://github.com/vercel/next.js) from 15.3.3 to 15.4.7.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.3.3...v15.4.7)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.4.7
  dependency-type: direct:production
...

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

Author: dependabot[bot]

demo/package.json

@@ -22,7 +22,7 @@
     "date-fns": "^4.0.0",
     "kurlar": "^1.0.2",
     "lucide-react": "^0.510.0",
-    "next": "15.3.3",
+    "next": "15.4.7",
     "next-themes": "^0.4.6",
     "prismjs": "^1.30.0",
     "react": "^19.0.0",