Update all CI images

Rebuild every CI image at a single new tag with a new Node.js version, driving the existing workflow_dispatch build workflows from a PR branch and babysitting the runs until they all pass.

Inputs

Parse from the user's invocation (ask only if missing):

• tag (required) — the Docker tag every image gets, e.g. 2025.06.0.
• node version (required) — full Node version, e.g. 22.22.1 (must exist at https://nodejs.org/dist/v<version>/ for both x64 and arm64).
• concurrency N (optional, default 4) — max build jobs in flight at once.

The job matrix — 6 builds total