A state directory with the wrong permissions left the terminfo cache
failing with errors that named no path, so there was nothing to act on:
$ ghostty +ssh-cache --add=user@host
Error: Unable to add 'user@host' to cache. Error: error.AccessDenied
Every +ssh-cache failure now names its cache file, and +ssh no longer
swallows cache-related errors.
Error messages in these actions are also lowercased after the "Error: "
prefix and append the error with ": {t}" rather than a second "Error: ".
Ref:
https://github.com/ghostty-org/ghostty/issues/9393#issuecomment-5145799368