Add tests

I do not think these type definitions work without `allowSyntheticDefaultImports`. I recommend adding some code that actually uses your type definitions with an appropriate `tsconfig.json`.

Start by reviewing the repository's type definitions and the expected use of an appropriate tsconfig.json, focusing on behavior with allowSyntheticDefaultImports disabled. Add usage code that exercises the definitions and make the tests demonstrate whether natural imports work without that option.

Written by the indexing model from the issue text.