Function finalize_upload_progress 

fn finalize_upload_progress(
    state_ref: &Arc<Mutex<AppState>>,
    batch_notify_ref: &Arc<Mutex<BatchNotifyState>>,
    sync_index_ref: &Arc<ShardedSyncIndex>,
    path: &str,
    success: bool,
) -> Option<u64>

Finalize upload progress: update counters, detect queue idle, return batch ID if a summary notification should be scheduled.