Brainstormed shape locked: chi route-group middleware, fail-closed
admin default; setup-token flow with 1h single-use tokens
(sha256-hashed at rest, raw shown to admin once); disable-only user
lifecycle with last-admin guard; self-service /settings/account
password change for every role; email field on users (metadata
v1); session re-validation on every authenticated request so
disable / role change land immediately.
Locked decisions captured in §Role taxonomy, §Schema changes,
§Setup-token flow, §RBAC enforcement, §Last-admin self-protection.
Deferred items in §Out of scope (OIDC, SMTP email-the-link,
hard delete, lockout).
Migrations 0017 (users extensions) + 0018 (user_setup_tokens)
both column-level ALTERs per CLAUDE.md preference.
