Both entry points ignored their arguments entirely, so the first thing a
contributor tries ran the real work: `python scripts/check.py --help` ran the
full dependency probe (and, on a host with a missing tool, exited 1), and
`python scripts/setup_wizard.py --help` entered the wizard -- which on an
existing config.yaml asks "Do you want to reconfigure?" and then rewrites
config.yaml and .env. Unknown flags were silently ignored the same way.
Parse arguments in the __main__ block, following scripts/doctor.py: main()
stays directly callable for the in-process unit tests, --help prints usage and
exits 0 before any probe or prompt, and an unknown flag exits 2 with
"unrecognized arguments". The no-argument invocations behind `make check` and
`make setup` are unchanged.
Adds subprocess CLI-contract cases in a disposable checkout next to the
existing script tests, modelled on backend/tests/test_doctor_script.py.
