chore(deps): update nextjs monorepo to v15.3.1

Author: renovate[bot]

package.json

@@ -46,7 +46,7 @@
     "@mui/lab": "6.0.1-beta.34",
     "@mui/material": "6.4.11",
     "@mui/material-nextjs": "6.4.3",
-    "@next/mdx": "15.2.4",
+    "@next/mdx": "15.3.1",
     "@rjsf/core": "5.24.8",
     "@rjsf/mui": "5.24.8",
     "@rjsf/utils": "5.24.8",
@@ -81,7 +81,7 @@
     "lodash-es": "4.17.21",
     "material-ui-popup-state": "5.3.5",
     "nanoid": "5.1.5",
-    "next": "15.2.4",
+    "next": "15.3.1",
     "next-http-proxy-middleware": "1.2.7",
     "nextjs-routes": "2.2.5",
     "node-fetch": "3.3.2",
@@ -101,7 +101,7 @@
   "devDependencies": {
     "@bufbuild/buf": "1.53.0",
     "@bufbuild/protoc-gen-es": "2.2.5",
-    "@next/bundle-analyzer": "15.2.4",
+    "@next/bundle-analyzer": "15.3.1",
     "@playwright/test": "1.51.1",
     "@squonk/eslint-config": "3.0.0",
     "dotenv": "16.4.7",