test(cli): add smoke tests to verify core commands

[jgafnea]

Adds minimal CLI smoke tests to verify the main entry point and subcommands are registered and parsed correctly.

Running the tests:

pytest tests/test_cli.py -v
tests/test_cli.py::test_cli_options[version] PASSED
tests/test_cli.py::test_cli_options[help] PASSED 
tests/test_cli.py::test_cli_commands[check] PASSED
tests/test_cli.py::test_cli_commands[apply] PASSED 
tests/test_cli.py::test_cli_commands[report] PASSED 
tests/test_cli.py::test_cli_commands[rollback] PASSED
tests/test_cli.py::test_cli_commands[list-rules] PASSED

Closes #3

[Aswinr24]

Hey @jgafnea this approach is pretty good
a minor change, otherwise looks good to merge

[jgafnea]

Changes applied.

[Aswinr24]

remove this comment

[Aswinr24]

the earlier request (including result.output in the exit-code assertion for debugging) still isn’t covered... could you switch to assert result.exit_code == 0, result.output and drop the Usage:/substring assert (not needed for this smoke test since we just want to confirm commands are registered and --help works)