Function load_composed_user_guidance 

pub fn load_composed_user_guidance(
    ito_path: &Path,
    artifact_id: &str,
) -> Result<Option<String>, WorkflowError>

Compose scoped and shared user guidance into one guidance string.

When both scoped and shared guidance are present, the returned text contains:

• ## Scoped Guidance (<artifact_id>)
• ## Shared Guidance

If only one source exists, that content is returned. If neither exists, returns None.