alice writes claim: "sky-color-40014631 is blue" on node-1
bob writes contradicting claim: "sky-color-40014631 is red" on node-2
  alice.id=f159d83e-668c-4271-b7e4-890c3471e2b1 bob.id=2c01620c-16ac-43f8-bfcf-774cfec20649
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