docs: align product docs with merged code (x402 2.1.0, wallet-cli 4.15.1, 8004 1.2.1, Agent Wallet 3.0.0) - #124

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@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/