Nock %fair (on-chain)

The strongest settlement in the stack: a witness-checked %fair consensus lock where the winning branch is enforced by consensus, not a trusted house signature. The house commits a seed before the round, the pot is locked in a 3-branch escrow on the Nock chain, both seeds are revealed, and only the matching winner's claim is accepted by consensus. In this demo the orchestrator supplies both seeds, so fairness is evidenced by the signed receipt chain rather than by an adversarial player. A stalled pot is recoverable via a timelocked refund branch; on-chain that leaf is outcome-blind, and it is house auto-recovery policy that never sweeps a pot the player won.