Function seed_ssr_cache_settings_from_env 

pub(crate) async fn seed_ssr_cache_settings_from_env(
    client: &Client,
) -> Result<(), AppError>

启动时用 SSR_CACHE_MAX_PAGE_BYTES、SSR_CACHE_EDGE_TTL_SECS 环境变量播种 SSR 页面缓存配置。