The milestone workbook becomes a from-scratch guide with the actual
code inline for every core stage: models, the real migration baseline,
read routes and the list page, mutations and minting, the badge
resolver (final mode-aware form), the single-commit ledger invariant,
RBAC gating, both kiosk endpoints with the wedge-input and focus-guard
mechanics, the 1x0.5in label CSS, and the reconcile query. Field
extensions stay summarized against their tags. New section: how to
contribute a plugin through GitHub (branch, stage commits, the three
CI gates, PR expectations, review checklist, and how publication
folds PRs into release commits).