docs(qa): correct eight identity-auth checklist items the 18.0 sweep measured as inaccurate

Checklist-accuracy findings of QA run #24538 (identity-auth, 5b14b7f),
each re-derived from source at 8fbbd50: invitation-scope-gates,
api-key-ui-lifecycle, org-membership-team-management,
self-service-password-reset, self-signup-gate,
auth-gate-held-session-raw-host-families,
default-organization-boot-invariant, self-service-profile-password.
One revision and one history row per item.

Claude-Session: https://claude.ai/code/session_01FM29ZqLTrnPNXxijioZwMp
Co-authored-by: Claude <noreply@anthropic.com>

Author: claude