Bump next from 15.5.7 to 15.5.9

Bumps [next](https://github.com/vercel/next.js) from 15.5.7 to 15.5.9.
- [Release notes](https://github.com/vercel/next.js/releases)
- [Changelog](https://github.com/vercel/next.js/blob/canary/release.js)
- [Commits](vercel/next.js@v15.5.7...v15.5.9)

---
updated-dependencies:
- dependency-name: next
  dependency-version: 15.5.9
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

apps/debug/package.json

@@ -11,7 +11,7 @@
   },
   "dependencies": {
     "backend": "workspace:*",
-    "next": "^15.5.7",
+    "next": "^15.5.9",
     "plugin-ui": "workspace:*",
     "react": "^19.2.1",
     "react-dom": "^19.2.1"