Function run_builder_task 

async fn run_builder_task(
    entry: BuilderEntry,
    version: String,
    dep_receivers: Vec<(String, Receiver<Option<bool>>)>,
    my_tx: Option<Sender<Option<bool>>>,
    log_tx: UnboundedSender<LogEvent>,
    on_event: impl Fn(BuildEvent) + Send + 'static,
) -> Result<Vec<ArtifactPath>>

Run a single builder inside a JoinSet task, handling dependency waiting, completion signalling, and reporting events back to the UI layer.