feat(datasource): 股票info字段放到API响应最外层

- yfinance_source.py: stock_info 存储在 df.attrs['info'] 中
- flask_server.py: dataframe_to_json 从 df.attrs 提取 info 放到最外层
- flask_server.py: 缓存切片函数保留 info 字段
- Dockerfile: 启用 Flask 服务作为默认 CMD（端口80）

响应结构示例:
{
  "data": [{"date": "2024-01-01", "code": "AAPL", ...}],
  "info": {"sector": "Technology", "industry": "...", ...}
}

Dockerfile

@@ -21,7 +21,7 @@ ENV TZ=Asia/Shanghai
 EXPOSE 80
 
 # 启动Flask数据API服务（默认端口80）
-# CMD ["python", "datasource/flask_server.py", "--host", "0.0.0.0"]
+CMD ["python", "datasource/flask_server.py", "--host", "0.0.0.0"]
 
 # 运行定时任务调度器（如需使用Flask服务，取消上面注释并注释掉下面）
-CMD ["python", "scripts/daily_scheduler.py", "--time", "09:00"]
+# CMD ["python", "scripts/daily_scheduler.py", "--time", "09:00"]