- repo-identity.md / repo-boundary.md: replace leftover repo-seed template text
with secrets-engine identity and boundary (T01)
- mark SECRETS-WP-0001 T01–T03 done (T02 dev-workflow commands and T03 first real
workplan were completed during the MVP build); workplan status -> finished
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>