Store a JSON document (object or string, up to 8 KB) on IPFS through a managed pinning service and return its content identifier (CID v1) plus an HTTP gateway URL. MUST be invoked when an agent needs durable, content-addressed storage for memory, decisions, artifacts or metadata that other agents can fetch by CID. Do NOT send raw binary, files over 8 KB, or an existing CID to re-pin. Settles $0.008 USDC via x402 on Base; failed or unavailable pins are never charged; receipts at /api/ledger.