Get a public redacted receipt proof

Anonymous public-safe proof view for a successful marketplace invocation. Successful execute, direct invoke, and x402 responses return receipt_id and receipt_url pointing at this route. The response includes a task summary, listing/provider identity, timestamp, latency, public cost and settlement rail, request/result/output hashes, receipt and invocation IDs, copy-paste curl/MCP snippets, and client-class/source tracking metadata. For x402 receipts, receipt.settlement.status reuses the durable invocation value: ordinary free invocations remain terminal settled, while granted World AgentKit trials remain free_trial, matching the immediate payment-response receipt metadata rather than changing from pending on later readback. These zero-dollar states do not claim that paid settlement occurred. It never exposes raw request payloads, raw provider output, buyer secrets, private customer data, raw payment payloads, wallet-private fields, settlement internals, or authenticated private receipt details.