pub fn parse_basic_credentials(headers: &HeaderMap) -> Option<(String, String)>Expand description
Parse a Basic <base64(user:pass)> Authorization header into
(username, password). Returns None if the header is missing,
malformed, or not Basic.
Provided as a free function so user-supplied FnAuthentication
closures (the recommended way to ship HTTP Basic Auth) can reach
it without re-implementing the boring base64 + colon-split logic.