Discover the URLs a page or sitemap points at in a single fetch. Point it at an XML sitemap or sitemap-index and it returns the <loc> URLs; point it at an HTML page and it returns the <a href> links — auto-detected. URLs are resolved to absolute, de-duplicated, fragment-stripped, and http(s)-only. `limit` (1-2000, default 200) caps the count; `sameHostOnly` keeps only links on the same host. Single SSRF-guarded fetch, no JavaScript, stateless — NOT a recursive crawler: to go deeper, call map again on a child sitemap or a discovered page. Returns { url, finalUrl, source: "sitemap"|"links", count, capped, urls }.