Implied volatility surface for BTC and ETH from Deribit options (public API, no auth). Returns ATM IV (annualized %), IV rank and IV percentile from Kronos iv_history (daily cron), term structure (weekly/1m/3m ATM IV + contango/backwardation/flat shape label), 25-delta risk reversal (BS-approximated strikes), 10-delta wing IVs, max-pain strike across top-5 expiries, and a vol-regime label. Falls back to OKX if Deribit is unreachable. $0.03 USDC via x402.