CI (FORCE_COLOR) renders --track-energy / --no-audit-log as split ANSI colour
segments, and monkeypatch.setenv with a null byte raises at setup on POSIX
(Windows tolerated both). Strip ANSI via a shared `_plain()` helper for every
--help substring assert, and rewrite the never-raises audit test to monkeypatch
append_audit_event to throw instead of injecting a null-byte env path.