Function make_on_pick 

fn make_on_pick(
    enabled: RwSignal<bool>,
    active_source_id: RwSignal<Option<String>>,
    error_message: RwSignal<Option<String>>,
) -> impl Fn(Option<String>) + Copy + Send + Sync + 'static

Closure factory for per-row click. Persists the new source and, if a session is live, tears down + restarts on the new source.