Added isDeviceSecure() method to SecurityModule interface for performing device-level security
checks such as jailbreak detection, device integrity validation, and other device-specific
security policies. Default implementation returns .allow.
Breaking Change: SecurityResult enum cases have been updated:
secure is now allow
insecure(String) is now deny(String)
Updated allowLogin() method documentation in SecurityModule to clarify that it returns
SecurityResult indicating whether login is allowed or denied with reason.
All SecurityModule methods now have default implementations that return .allow by default to
ensure safe fallback behavior.