docs(kickoff): wire the pi-review secret during Step 8
Every fork needs MINIMAX_API_KEY before pi-review.yml can run; repo
secrets don't inherit. Step 8 now sets it right after the remote is
created (op read from 1Password piped to gh secret set) and the hand-back
checklist verifies it — or it's carried as an unchecked follow-up item
when op is unavailable or the remote was deferred.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>