build(deps): bump next from 15.5.9 to 15.5.15

Bumps [next](https://github.com/vercel/next.js) from 15.5.9 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](https://github.com/vercel/next.js/compare/v15.5.9...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>

package.json

@@ -46,7 +46,7 @@
     "firebase": "^11.10.0",
     "genkit": "^1.24.0",
     "lucide-react": "^0.475.0",
-    "next": "^15.5.9",
+    "next": "^15.5.15",
     "openai": "^5.10.1",
     "patch-package": "^8.0.1",
     "react": "^18.3.1",