Plan if Kitchen could be static or not

It is unlikely that new Kitchens will have to be added by users. It would be easier if we don't allow the creation of new kitchens. We would not have to deal with validating uniqness, and other things.

Start by reviewing how Kitchens are created and how uniqueness is validated. The issue proposes deciding whether user-created Kitchens should be disallowed, but names no files, tests, or concrete acceptance criteria. Done would require a settled decision and defined implementation scope.

Written by the indexing model from the issue text.