test_python_imports_supervise_module probed the image with
`import supervise; import supervise_server`, the flat sibling modules that
5ad3449 replaced. They now live in the installed package, so the test fails
with ModuleNotFoundError when actually run.
It went unnoticed because the whole class carries a GITEA_ACTIONS skip — it
is interactive-only, so CI never executes it.
All 4 tests in the class now pass against a freshly built gateway image.
Closes#429.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>