pub fn parse_handle(s: &str) -> Result<Handle>Expand description
Parse nick@domain. Returns Err on malformed inputs or reserved nicks.
Nick rules: 2-32 chars, [a-z0-9_-]. Domain rules: DNS-label-shaped,
dot-separated, lowercase ASCII — OR (E4) a loopback authority with a port
(127.0.0.1:PORT / localhost:PORT) for a local-dev / sandbox relay. We
don’t fully validate domain syntax here — DNS resolution will fail later if
the operator typo’d it.