- docs/API.md: complete API reference (auth/identities/tickets/bans/users/
settings/notifications/polls/features/export/captcha/uploads/external/
install/health) with auth, rate limits, roles, data migration notes
- auth.js register: also check user_identities for duplicate game_name
(multi-identity compat for old data backfilled into new table)
- README: link API docs, multi-identity section
