PR previews are wiped on each production docs deploy #702

Problem

PR preview deployments (under pr-preview/) on the gh-pages branch are wiped out every time a production documentation release runs.

The root cause is that the production deploy uses mkdocs gh-deploy, which delegates to ghp-import under the hood. ghp-import offers no option to exclude a directory from being overwritten — it replaces the entire branch content on each deploy.

This was identified as a follow-up to #701.

Possible solution

Switch the production deploy step in release-management.yml from mkdocs gh-deploy to JamesIves/github-pages-deploy-action@v4 with the following options:

• clean-exclude: pr-preview — preserves the pr-preview/ directory across deploys
• force: false — avoids force-pushing, which is compatible with how pr-preview-action manages the branch

See also: https://github.com/rossjrw/pr-preview-action?tab=readme-ov-file#ensure-your-main-deployment-is-compatible