fix(deps): update nextjs monorepo to v15.5.6

Signed-off-by: Renovate Bot <[email protected]>

Author: renovate[bot]

frontend/package-lock.json

@@ -15,7 +15,7 @@
     "clsx": "^2.1.1",
     "date-fns": "^4.1.0",
     "lucide-react": "^0.542.0",
-    "next": "15.5.0",
+    "next": "15.5.6",
     "react": "19.1.1",
     "react-dom": "19.1.1",
     "tailwind-merge": "^3.3.1",
@@ -28,7 +28,7 @@
     "@types/react-dom": "^19",
     "autoprefixer": "^10.4.21",
     "eslint": "^9",
-    "eslint-config-next": "15.5.0",
+    "eslint-config-next": "15.5.6",
     "postcss": "^8.5.6",
     "typescript": "^5"
   }