Link preview for any web page: fetches a URL and parses only the <head> (no JS, no rendering). Returns title, meta description, canonical URL, language, an always-absolute favicon, all Open Graph and Twitter Card tags, and RSS/Atom/JSON-feed links. Tolerant of messy real-world HTML and non-UTF-8 charsets. The caller-supplied URL is SSRF-checked; the fetch is capped at 5 MB and 8 s.