add back re-written release doc

[rlnsy]

Summary

Describe what you changed and why.

Section

• Playbook
• Showcase
• Contribute
• Agents
• Templates
• Archetypes
• Standards

Required Metadata Checklist

• title included
• description included
• last_reviewed uses YYYY-MM-DD
• authors included for module pages (registered IDs)

Quality Checklist

• Followed template format
• Added/updated links with context
• Did not introduce unused tag metadata
• Ran npm run check

[vercel]

@rlnsy is attempting to deploy a commit to the Mateusz Faltyn's projects Team on Vercel.

A member of the Team first needs to authorize it.

[mattfaltyn]

Restores a rewritten Build-phase Release Guide and wires it into the human playbook tree plus sidebar tests. Frontmatter is valid (rowan-lindsay is registered), slug/docId/route line up, and validate-build-and-test is green.

Non-blocking follow-ups, not merge blockers:

• A few grammar nits in the new page (it's potential impacts → its; may or not → may or may not; is it build correctly → built).
• The description calls this a checklist, but the body is a decision framework without an enumerated checklist.
• docs/human/playbook/build/build.md still does not link here even though it talks about release decisions.
• Vercel preview is waiting on first-time deploy authorization; that status is not required to merge.