URL parser: parse and canonicalise a URL, and extract its registrable domain using the Public Suffix List — the part an agent needs to decide whether two URLs belong to the same owner. Returns scheme, host, port, path, decoded query parameters and fragment, the public suffix, the registrable domain (eTLD+1), the subdomain, whether the suffix is ICANN or private, plus a canonical form with default port, dot-segments and percent-encoding normalised. unicode_host uses WHATWG/UTS 46 (non-strict).