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 using planner-driven sequencing.

Used for the explicit-IDs path (oven on 42,43). Calls the planner with no in-flight context, builds a DependencyGraph, then runs layers sequentially (issues within each layer run in parallel). Falls back to all-parallel if the planner fails.