Post-review fixes:
- Phase 2 no longer breaks early when only --fail_marker is set: the
'if not args.pass_marker: break' guard skipped all output reads, so a
fail marker was never detected (exit 0 instead of 1). Now breaks only
when neither pass nor fail markers are configured.
- docstring referenced --pass/--fail; argparse registers
--pass_marker/--fail_marker. Align the docstring.
- retry echo said 'attempt N/3' but the loop limit is 5 attempts; say /5.
- warn and skip malformed steps (missing expect:/send: prefix) instead of
spinning in select until timeout.
vasilito
cf6f363da9