A股/美股行情数据获取工具集 — 交易日检查、指数/板块/涨停池/北向资金数据拉取，基于 AKShare（免费、无需 token）。Use when the user needs free A-share/US market snapshots: trading-day checks, index/sector/limit-up-pool/northbound data, or per-stock daily OHLCV.
