Probably a new skill called usethis-python-enum

Originally encountered here:

@copilot Please add a unit test that checks this dict is comprehensive, i.e. its keys are the same as the enum elements

Originally posted by @nathanjmcdougall in #1469 (comment)

Type checkers will capture a lot of patterns if we are careful. The assert_never pattern used in the codebase, etc.

There's this particular example of a dict with an enum key, which deserves a dedicated unit test to ensure it's kept updated to ensure complete coverage over the enum