NativeKeyboardBehavior

Configures the native soft keyboard for the field: layout, return key, capitalization, autofill, and smart features. The single composable home for keyboard traits — the editor reads it when it shows the keyboard. The traits apply both in the default transparent-keyboard mode and when a NativeFieldOverlayBehavior renders the OS's own field. Password masking is a separate concern (PasswordBehavior). Desktop has no soft keyboard — the behavior is inert there.