Update nextjs monorepo to v15.5.8

Author: renovate[bot]

package-lock.json

@@ -15,7 +15,7 @@
   },
   "dependencies": {
     "@opennextjs/cloudflare": "1.3.1",
-    "next": "15.4.5",
+    "next": "15.5.8",
     "react": "19.1.0",
     "react-dom": "19.1.0"
   },
@@ -26,7 +26,7 @@
     "@types/react": "19.1.8",
     "@types/react-dom": "19.1.6",
     "eslint": "9.30.1",
-    "eslint-config-next": "15.4.5",
+    "eslint-config-next": "15.5.8",
     "tailwindcss": "4.1.11",
     "typescript": "5.8.3",
     "wrangler": "4.22.x"