chore(release): finalize Registry Stack v0.12.0 source

[jeremi]

Summary

Finalize Registry Stack beta-14 after promotion PR #422 merged to protected main as 0a20f7a81d8ca2fccb70d8f4c088ff5acaf5f66f.

• pin the beta-14 manifest and v0.12.0 archived docs to that promotion squash commit
• regenerate the three source-ref-sensitive docs data artifacts
• remove the exact one-time Notary OpenAPI promotion exception
• close a confirmed pre-tag release blocker by publishing and verifying OCI source, revision, and version labels on both release images

The manifest remains release-candidate; hosted/public and Solmara holds remain unchanged.

Verification

• 60 release-tool unit tests
• manifest validation and 8 versioned docsets
• import-map audit and monorepo source proof
• normal Notary OpenAPI comparison against 0a20f7a8
• latest and v0.12.0 docset checks
• 117 docs tests
• v0.12.0 archive build
• all historical archive builds
• SEO validation across 225 latest and 2,841 archived pages
• 490,535 internal links and assets
• Actionlint
• git diff --check

Signed-off-by: Jeremi Joslin jeremi@joslin.fr