Whole-file configuration for the OpenStack client, including clouds, cache, and client settings.
Do not include passwords, tokens, or application credential secrets here, as they will be publicly readable in the Nix store. Use the runtime environment or an externally managed secure.yaml file. Configuration written to $XDG_CONFIG_HOME/openstack/clouds.yaml. See https://docs.openstack.org/python-openstackclient/latest/configuration/index.html#clouds-yaml.