alice writes M1 on node-1
  M1 id=a7734948-9c3a-49b7-91f4-4f2db949b524
settle 5s for pre-archive replication
alice archives M1 via DELETE /api/v1/memories/{id} (soft-delete → archive)
  archive (DELETE) returned HTTP 200
settle 5s for archive propagation
bob queries /api/v1/archive on node-2
  bob sees M1 in archive: False
charlie restores M1 via /api/v1/archive/{id}/restore on node-3
  restore returned HTTP 404
settle 5s for restore propagation
node-4 aggregator: M1 must be active again
  node-4 active rows matching marker: 0
fetch /api/v1/archive/stats on node-4