Function load_command_with_env 

pub fn load_command_with_env(
    dir: &Path,
    env: Option<&str>,
) -> Result<CommandConfig, String>

Load a sub-command config with an optional environment overlay.

Applies the same .example/.dist fallback as find_config to locate the base file, then deep-merges a sibling fdl.<env>.yml overlay if one exists. A missing overlay is silently accepted here (different from load_project_with_env) — envs declared at the project root don’t have to exist for every sub-command.