Add GraphQL & AI subpage (/ai) with interactive demos - #2469

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-node@cdca7365b2dadb8aad0a33bc7601856ffabcc48e, pnpm/action-setup@a7487c7e89a18df4991f7f222e4898a00d66ddda, styfle/cancel-workflow-action@85880fa0301c86cca9da44039ee3bb12d3bedbfa. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/