Add tests to examples

It would be useful to have an example where docker is used for running tests -- i.e. the app and the test directory are installed/mounted on the image and the last directive calls `uv run pytest ...`.

Start by reviewing the repository's existing Docker examples and identify where example images and test commands are defined. Add an example that mounts the app and test directory into the image and ends with `uv run pytest ...`; done means the example can run the tests through Docker.

Written by the indexing model from the issue text.