chore(m171): open — CLI argument rejection uniformity

Spec moves pending/ -> active/, Status IN_PROGRESS, branch recorded,
and the Zig test baseline captured for the VERIFY Test Delta. The diff
is TypeScript-only, so the Zig counts are expected to stay flat; CLI
test growth is the meaningful delta and is graded via make test-unit-all.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>