Live EVM transaction status and receipt lookup. Give a transaction hash + chain and get back whether it mined successfully, reverted, or is still pending in the mempool, plus block number, confirmations, timestamp, sender and recipient, value transferred (native unit), gas used, effective gas price, total fee paid, any contract created, and event-log count. Chains: base, ethereum, polygon, arbitrum, optimism. Real-time post-training chain state — use it to confirm a payment settled, detect a reverted transaction, or wait for confirmations before acting. Unknown hash returns 404. Sibling of /api/crypto/gas-oracle (fees) and /api/crypto/address-validate (format).