Prevent merged PR cleanup from cancelling docs deployment

[uriahf]

What changed

• use one shared concurrency group for documentation writes
• queue documentation deployments instead of cancelling an in-progress deployment

Why

When a PR is merged, GitHub emits both:

1. a push to main, which builds and publishes production docs
2. a closed pull-request event, which removes the PR preview

For a merged PR, both runs resolve to the same previous concurrency key. Because cancel-in-progress was enabled, the preview-cleanup run cancelled the production deployment. This happened after both PR #282 and PR #283.

Serializing the runs prevents concurrent writes to gh-pages and ensures neither production publishing nor preview cleanup is dropped.

Validation

• package CI after PR Separate PyPI publishing from package CI #283 passed
• the cancelled production run and successful closed-event cleanup started at the same timestamp
• this change is limited to the documentation workflow concurrency policy

[github-actions]

PR Preview Action v1.8.1
Preview removed because the pull request was closed.
2026-08-11 03:43 UTC