We generally consider the use of phan as "best practice", but we don't seem to document/list it as part of the extension deployment checklist etc
To the best of my knowledge the canonical documentation would be https://www.mediawiki.org/wiki/Writing_an_extension_for_deployment
The various tools we recommend on repositories are listed at https://www.mediawiki.org/wiki/Continuous_integration/Entry_points and the documentation we have for Phan: https://www.mediawiki.org/wiki/Continuous_integration/Phan
So I guess one can amend Writing an extension for deployment and an entry to the check list there?
Tagging Wikimedia-extension-review-queue which is used to track that process.