Function fetch_feeds 

pub async fn fetch_feeds(
    urls: &[String],
    params: &FetchParams,
    cache: &Cache,
) -> FetchOutput

Fetch and parse many feeds concurrently, returning the full structured output.

Partial failure is the norm: a feed that errors becomes a FeedStatus::Error entry (and is mirrored into FetchOutput::errors); successful feeds are unaffected.