CI: fail when the upstream name appears in a new string literal

tools/fork/name-check.py reads every string literal in crates/ (comments
and test directories skipped) and fails on any that carries the upstream
name without an entry in name-allowlist.txt. An upstream merge can bring
such strings in without a conflict, so it runs on every push and PR.

The first run found three the earlier sweeps missed, fixed here: the SMTP
HELP reply pointed at upstream's website (now brand_url!), the event
collector thread was named after upstream, and the FreeBSD default data
path still said /var/db/stalwart/ where Linux already had /var/lib/inbuxa/.

Two operator-visible defaults are allowlisted as open, pending a decision:
the log file prefix and the SQL stores' default database and user.

crates/smtp/src/inbound/session.rs

@@ -211,7 +211,7 @@ impl<T: SessionStream> Session<T> {
                             Request::Help { .. } => {
                                 trc::event!(Smtp(SmtpEvent::Help), SpanId = self.data.session_id,);
 
-                                self.write(b"250 2.0.0 Help can be found at https://stalw.art\r\n")
+                                self.write(concat!("250 2.0.0 Help can be found at ", types::brand_url!(), "\r\n").as_bytes())
                                     .await?;
                             }
                             Request::Helo { host } => {