feat: add niuone US market + X timeline sources on HF tip

Add ETF premium and HK short selling sources

Limit default AI search to fastest site

Prefer fast AI hub search for GET endpoint

Optimize search GET fallback and data source stability

Add fleur-derived data endpoints and source fallbacks

fix: 引入全局源调用池，防止 HF Pro tier worker pool 饱和

feat: 股指期货基差接口支持多日历史查询

feat: 新增股指期货基差接口 /market/futures-basis

fix: 修复宏观数据排序 + 添加全量缓存清除接口

refactor: swap chip endpoints — CYQ precise becomes /chip default

feat: add chip-cyq endpoint (precise chip distribution via CYQ algorithm)

feat: add income, balancesheet, daily-basic endpoints

feat: add AI-Search-Hub multi-platform search integration

fix(api): encoding, financial history, fund-flow & report resilience

Add Shenwan industry, fund holdings, and fund structure endpoints

Add big-deal endpoint and fix SZSE margin date selection

Add margin, northbound, and shareholder endpoints

Add ETF realtime quote endpoint with source rotation

Apply fixes: search SSE streaming, fund-flow fallback, default search config