Current price, market cap, and 24h change for a cryptocurrency, from
CoinGecko. Use for "price of bitcoin", "how much is ETH worth", "what's
solana trading at" style questions. `coin` is CoinGecko's own lowercase
slug (bitcoin, ethereum, solana, dogecoin, ...) -- a handful of common
tickers (BTC, ETH, SOL, DOGE, XRP, ADA, BNB, USDT, USDC, LTC) are mapped
to their slug automatically as a convenience, but anything else must be
the exact slug, not a ticker. `vs_currency` defaults to "usd" and
accepts any fiat CoinGecko supports (eur, gbp, jpy, ...). Returns price,
market cap, and 24h % change; prices are informational only, not
investment advice.