Function exec_command 

pub fn exec_command(
    cmd_config: &CommandConfig,
    preset_name: Option<&str>,
    extra_args: &[String],
    cmd_dir: &Path,
    project_root: &Path,
) -> ExitCode

Execute a sub-command, optionally with a named preset (inline command).

project_root is needed to resolve Docker compose context and compute the relative workdir for containerized execution.