v1.6.4

Fixed

• Standalone owner-chat access tokens persist across service restarts in the
  existing private owner-chat.json file, so saved chat URLs keep working with
  a fixed listener port. Concurrent first starts share one token, changing the
  listener port preserves it, and invalid or unsafe credential files are rejected
  rather than silently replaced. Token rotation is now an explicit action.

macOS: Developer ID-signed but not notarized. Apple's team-enrollment rejection is unresolved; notarization is temporarily disabled.