feat: release safe legacy migration and publication gate

[saintdle]

Outcome

Prepare Agentflow 0.0.2 with a transactional legacy-install cutover, rollback, full-history privacy gate, explicit third-party provenance, and development/testing-only AI-authorship disclosure.

Safety boundary

• Replaces only exact symlinks owned by a recognized legacy checkout.
• Preserves unmanaged/domain skills and all project, Beads, session, evidence, credential, and Git state.
• The live legacy installation was dry-run only; no apply or rollback was performed.
• No tag, release, or merge is part of this PR.

Evidence

• 446 unit tests passed (1 skipped).
• python3 scripts/validate.py passed.
• v0.0.2 wheel/sdist inspection passed.
• Clean-wheel smoke passed, including packaged synthetic migration apply/rollback.
• Final all-refs scan inspected 194 unique historical blobs with the local private denylist: no findings.
• git diff --check passed.

Provenance

Attributes the adapted to-tickets, code-review, diagnosing-bugs, and wayfinder skills to Matt Pocock and the MIT-licensed mattpocock/skills repository, with skill-local notices and validator enforcement.