Function next_pending_task 

fn next_pending_task(
    config: &ImportResumeConfig,
    state: &ImportState,
    next_idx: &mut usize,
    progress: &dyn ProgressReporter,
) -> Option<usize>

Returns the index of the next task eligible for import, scanning forward from next_idx and skipping tasks already marked Completed (counting each skipped task once toward progress). Advances next_idx past the returned task so each task is scheduled at most once.