Merkle inclusion playground

Every node of an rr-trace/3 reasoning DAG — claim, each stance, each piece of evidence, each counter-argument, each sensitivity factor, each critic dimension — has its own SHA-256 hash. A Merkle root over all the node hashes is committed on Arc inside ReceiptRegistryV2. Pick any receipt and any node id; the server pulls the trace from Irys, builds the inclusion proof, verifies it locally, and then callsverifyInclusion(root, leaf, proof)on Arc via eth_call. You get a yes/no from the contract itself — no full-trace download required.