Fix what a newcomer install actually hits: source builds, gateway routing, and URLs that name the wrong host - #10

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@11d5960a326750d5838078e36cf38b85af677262, azure/setup-helm@1a275c3b69536ee54be43f2070a358922e12c8d4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/