cluster: opt-in q8 activations on the wire (COLI_CLUSTER_ACT=q8), protocol v2 - #1963

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