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

fix: 修复宏观数据排序 + 添加全量缓存清除接口

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

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

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