Add smoke tests on the generated docker image

[gwleclerc]

Could be linked to ant-design/parcel-antd#12 (which should also reduce bundle size)

[gwleclerc]

It works and bundle size is reduced from 3.75MB to 2.4MB

[Thiht]

We should add UI smoke tests

[gwleclerc]

We should add smoke tests for the UI and the server using the docker image.
Could be done with venom by calling the pages.

OR we could test cypress.io which looks amazing for UI testing 😉

[gwleclerc]

Done. The generated Docker image is now smoke-tested in CI:

• chore: fixes, self-contained scratch image, and dev-flow improvements #325 added the smoke test in the build job — it starts the container and checks that the config API answers, the embedded UI is served, and a mock registered on the config port round-trips through the mock port.
• ci(docker): smoke-test the image before publishing it #330 extended it to run before publishing: the deploy job builds the native image from the release artifact and runs the same smoke test, so a broken image can never reach the registry.

Closing as addressed.