feat: add Gateway API HTTPRoute support with optional self-managed Gateway - #100

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-python@v5.3.0, azure/setup-helm@v4.3.0, helm/kind-action@v1.12.0. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/