[] Create a production deployment tracking task to get an extension into the review queue: https://phabricator.wikimedia.org/maniphest/task/edit/form/1/?projects=Wikimedia-Extension-setup,wikimedia-extension-review-queue
[x] Pass security review (not needed as per T277690)
[x] Pass performance review (T305615)
[x] Pass design review (not relevant; no design in the extension - the echo notifications will be reviewed by design separately)
[x] Pass DB review (not relevant; no schema changes)
[] Restore, update & merge CI updates: https://gerrit.wikimedia.org/r/c/integration/config/+/766605
[] Restore, update & merge inclusion in release tool: https://gerrit.wikimedia.org/r/c/mediawiki/tools/release/+/766613
[] Wait at least 2 weeks after merging above patch, until extension code is branched & deployed (unused) in production
[] Restore, update & merge extension-list entry and config var: https://gerrit.wikimedia.org/r/c/operations/mediawiki-config/+/766615
[] Enable on beta cluster (InitialiseSettings-labs.php in operations/mediawiki-config) on relevant wikis with whatever config is needed for this extension
[] Enable on production cluster (InitialiseSettings.php in operations/mediawiki-config) on relevant wikis with whatever config is needed for this extension
[] Update [mw.org/Extension:ImageSuggestions](https://www.mediawiki.org/wiki/Extension:ImageSuggestions), adding the `{{OnWikimedia}}` template & whatever additional config & information are relevant for this extension
[] Double-check https://www.mediawiki.org/wiki/Writing_an_extension_for_deployment#Preparing_for_deployment to make sure nothing has been forgotten