fix: migrate OpenRouter verification to authenticated JSON APIs - #5

Node.js *** is deprecated. The following actions target Node.js *** but are being forced to run on Node.js 24: actions/checkout@v4, dorny/paths-filter@v3. For more information see: https://github.blog/changelog/***25-***9-19-deprecation-of-node-***-on-github-actions-runners/