BTC Up or Down - 15 Minutes

This market will resolve to "Up" if the BTC price at the end of the 15-minute window is greater than or equal to the price at the beginning. Otherwise, it will resolve to "Down". The resolution source is Chainlink Data Streams (same as Polymarket). Start price is captured at market start; end price is captured at market end. An unchanged price counts as Up. Verification: https://www.okx.com/trade-spot/btc-usdt