Add Kondo linter to make sure namespace doesn't require itself

Can probably actually be submitted as a PR against Kondo itself. I think there's an open issue for this.

The issue names Kondo as the linter and says the change may belong in Kondo itself, with an existing Kondo issue possibly tracking it. Start by locating that issue and confirming the target repository; no Metabase files, tests, entry points, or completion criteria are provided here.

Written by the indexing model from the issue text.