Function get_biz_group 

pub async fn get_biz_group(
    client: &Arc<FutuClient>,
    env: &str,
    acc_id: u64,
) -> Result<String>

v1.4.95 U1: MCP tool futu_get_biz_group — 业务分类元数据.

给 client 构造 cash log 过滤下拉菜单用 (业务分组 / 货币 / 方向).