constructing 500-row bulk payload
staging bulk payload on node-1 /tmp, then POST /api/v1/memories/bulk
  bulk POST returned HTTP 200
settle 20s for bulk fanout across 3 peers + aggregator
  node-2 count=0 (expected 500)
  node-3 count=0 (expected 500)
  node-4 count=0 (expected 500)