alice writes claim: "sky-color-1b83efa3 is blue" on node-1
bob writes contradicting claim: "sky-color-1b83efa3 is red" on node-2
  alice.id=dcd3feae-2884-4b8a-97e2-1e38724159e8 bob.id=44751cbc-7149-4157-9851-72fce6f4ab35
settle 10s for quorum fanout + contradiction indexing
charlie queries /api/v1/contradictions on node-3
  HTTP 200
  sees both memories: True; sees contradicts link: True