Upgrade Node from 22.x to 24.x (blocked by graphql-shield's util.isUndefined import)

[gennitdev]

Summary

The backend pins engines.node to 22.x (package.json), while the frontend (multiforum-nuxt) requires Node ≥ 24.13.0. Contributors who work across both repos have to keep switching Node versions with nvm, which is error-prone. We should upgrade the backend to Node 24.x so the whole project lines up on one major.

Why it isn't already on 24

Running under Node 24 crashes at module-load time:

SyntaxError: The requested module 'util' does not provide an export named 'isUndefined'
  at .../node_modules/graphql-shield/esm/rules.js:3
    import { isUndefined } from 'util';

graphql-shield@7.6.5 (used by permissions.ts) does import { isUndefined } from 'util'. util.isUndefined was long-deprecated and is no longer exposed as a named ESM export under Node 24, so anything that imports the resolvers/permissions fails to load. This blocks the server and the integration test harness on Node 24; the tests only run on Node 22 today.

Proposed work

• Upgrade / replace graphql-shield (or patch the util.isUndefined import) so it loads under Node 24.
• Bump engines.node to 24.x and update any .nvmrc / CI Node version.
• Re-run the integration test suite (npm run test:integration, testcontainers + Docker) on Node 24 and fix any other Node 24 incompatibilities that surface.
• Verify the dev server and Heroku/CI build on Node 24.

Impact

Once done, both repos use Node 24 and contributors no longer need to swap Node versions between frontend and backend work.