alice writes claim: "sky-color-ff00a0ce is blue" on node-1
bob writes contradicting claim: "sky-color-ff00a0ce is red" on node-2
  alice.id=d1243f71-4e50-4647-ab67-43e404fcf20f bob.id=907d78c7-2a73-4506-aaa6-eb5bb43e45a3
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