pub const URL_PATTERN: &str = r"^https?://[A-Za-z0-9._~:%/?#\[\]@!$&'()*+,;=-]+$";Expand description
URL validator — http(s) only, requires a host, accepts an
optional path/query/fragment. Conservative on purpose:
ftp://, mailto:, etc. get rejected so a form that promises
“URL” doesn’t end up persisting a non-web scheme.