Function resolve_language 

pub fn resolve_language(
    force_lang: Option<&str>,
    config_dir_override: Option<&Path>,
) -> Language

Resolves language using the CLI / XDG / OS / default precedence hierarchy.

config_dir_override is the same optional directory used by --config-dir (tests / isolation). When None, XDG via directories applies. Product does not read SSH_CLI_HOME or SSH_CLI_LANG as config stores.