Function run_batch 

pub async fn run_batch<R: CommandRunner + 'static>(
    executor: &Arc<PipelineExecutor<R>>,
    issues: Vec<PipelineIssue>,
    max_parallel: usize,
    auto_merge: bool,
) -> Result<()>

Run the pipeline for a batch of issues, limiting parallelism with a semaphore.

Used for the explicit-IDs path (oven on 42,43). For the polling path, see polling_loop which handles continuous issue discovery.