Joseph Doherty
6ebe791c6d
feat: add authenticators, Account, and ClientPermissions (Tasks 3-7, 9)
- Account: per-account SubList and client tracking
- IAuthenticator interface, AuthResult, ClientAuthContext
- TokenAuthenticator: constant-time token comparison
- UserPasswordAuthenticator: multi-user with bcrypt/plain support
- SimpleUserPasswordAuthenticator: single user/pass config
- NKeyAuthenticator: Ed25519 nonce signature verification
- ClientPermissions: SubList-based publish/subscribe authorization