github-actions-parallelize

# GitHub Actions parallel steps Steps can run concurrently within one job, with separate logs and execution: - `background: true`: starts a step asynchronously; execution proceeds immediately. - `wait`: blocks until specific named background steps finish. - `wait-all`: blocks until all earlier background steps finish. - `cancel`: gracefully stops a background step, including a long-running service. - `parallel`: groups concurrent steps and waits for the group to finish; shorthand for background steps followed by a wait. Reference: [workflow syntax](https://docs.github.com/en/actions/reference/workflow-syntax-for-github-actions).