* fix(scripts): make doctor.py --help print usage without running diagnostics
scripts/doctor.py never parsed its arguments: `python scripts/doctor.py
--help` printed no usage and ran the whole diagnostic suite (subprocess
probes, config resolution, provider checks) and exited 0; any unrecognized
flag was silently ignored the same way. Closes#7386.
- Parse arguments with argparse.ArgumentParser in the __main__ entry point:
--help prints usage and exits 0, unknown flags exit 2.
- The no-argument invocation used by `make doctor` is unchanged, and main()
stays directly callable from the existing unit tests (they run in-process
under pytest, whose argv must not reach argparse).
- Add backend/tests/test_doctor_script.py: offline subprocess cases for
--help (usage, no diagnostics run), an unknown flag (exit 2), and the
no-argument run (report footer present, exit 0 or 1).
* test(scripts): isolate doctor CLI subprocess checks
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Co-authored-by: Willem Jiang <willem.jiang@gmail.com>
