Pull and clean the BTC or ETH options chain from Deribit, with proper inverse-quote handling and downstream-ready columns. Use this skill whenever the user wants the full Deribit options chain, a single expiry, an ATM strip, or a chain filtered by liquidity. Triggers: "Deribit chain", "BTC options chain", "ETH chain", "show me 26DEC25 BTC strikes", "what's on Deribit for BTC right now", "0DTE BTC options". Defaults: currency = BTC, nearest 4 weekly + nearest 4 monthly expiries, bid/ask spread filter 30%.
