The lone test (`test_router`) has been failing for the lifetime of
the repo. It's `@pytest.mark.asyncio`-decorated but the project
deliberately doesn't ship `pytest-asyncio` (newer tests use
`asyncio.run` inside the body — see `test_cassette_state_consumer.py`
header), so the test is uncollectable in our runner. The body asserts
nothing the extension-load boot path doesn't already cover.
After this: full suite is 155/155 green. Closes#34.
