> a project isn’t dying because of no commits. Rather it’s stable

Agreed. Assuming there are no open issues and PRs. When I find a project, if the date of the last commit is old, I next look at the issues and PRs. If there are simple-to-deal-with issues (e.g. a short question or spam) and easy-to-merge PRs (e.g. fixing a typo in the README) which have been left lingering for years, it’s probably abandoned. Looking at the maintainer’s GitHub activity graph should provide more clues.

> I often feel I need to setup bots to make superfluous commits just to make it look like my useful and stable repos are “active”

I have never done it, but a few times thought about making a “maintenance” release to bump the version number and release date, especially since I often use a variant of calendar versioning.