Reason:
It has been created in 2014 and has not been continued.
https://wikiapiary.com/wiki/Extension:VisualChat shows no deployment.
- Archive documentation on mediawiki.org https://www.mediawiki.org/wiki/Extension:VisualChat
- Remove from mediawiki/extensions (along with in .gitmodules)
- Remove tests in integration/config (zuul/layout.yaml)
- Remove from translatewiki (groups/MediaWiki/mediawiki-extensions.txt)
- Empty repository and add a OBSOLETE file.
- Archive the extension's diffusion repository: rEVCH
- Mark the repository read-only in Gerrit: https://gerrit.wikimedia.org/r/#/admin/projects/mediawiki/extensions/VisualChat
- Delete the GitHub mirror: https://github.com/wikimedia/mediawiki-extensions-VisualChat