Centralized-exchange OHLCV candlesticks for a spot trading pair (e.g. BTC-USD, ETH-USD, SOL-USD), free/keyless. Pass interval (1m/5m/15m/1h/6h/1d) and limit. Each bar: time, open, high, low, close, volume. Net-new vs crypto.dex-ohlcv (on-chain DEX) — this is CEX spot.