/gflow:live-verify — Live-verification enforcement

gflow-cli reverse-engineers a blackbox: Google Flow. Offline checks (ruff, pyright, unit/BDD tests) verify gflow-cli's own code does what it's supposed to; they cannot verify Flow still behaves the way it was captured, because Flow is external and changes without notice (see #174). This gate enforces two things, both evidence-based (no claim without a fresh verification artifact — see the superpowers:verification-before-completion skill):

1. Part 1 — Pre-flight, at the start of feature/fix work: confirm the checkout reflects current develop before investing effort.
2. Part 2 — Live-verify, before claiming done (after /code-review and /ponytail:ponytail-review, before commit/PR): exercise the change against real Flow.

Full design rationale: docs/superpowers/specs/2026-07-19-live-verify-design.md.