Function save_with_slug 

pub fn save_with_slug(
    dir: &Path,
    store: &Store,
    slug: &str,
    name: &str,
    graph: &FlowGraph,
    collection_slug: &str,
    source: Option<TemplateSource>,
) -> Result<TemplateRecord, TemplateError>

Lower-level save that takes an explicit slug instead of deriving one. Used by the Hub install path, where the catalog slug must stay stable across versions even when the display name changes. slug is validated against the same [a-z0-9-]+ rule as the renderer-facing routes.