Clippy sweep: clean across the workspace

- Box the oversized enum variants (Event::AccountRegistered, gossip
  Msg::Entry) so small events aren't sized to a full Account; serde is
  transparent so the wire/log format is unchanged.
- Use the configured server description in the SERVER line (it was
  hardcoded and the config field went unread).
- Derive the ChanServ SET label from the ChanSetting (drops toggle's 8th
  arg); rename inspircd from_us -> sourced.
- allow the two framework-idiom lints with rationale (tonic's Status in
  authorize; the guest-rename handler's inherent arg count).
- Auto-fixed map_or/contains/split_once style lints.

nickserv/src/ungroup.rs

@@ -12,7 +12,7 @@ pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx, db:
         ctx.notice(me, from.uid, "You can't ungroup your main account name.");
         return;
     }
-    if db.resolve_account(nick).map_or(true, |a| !a.eq_ignore_ascii_case(account)) {
+    if db.resolve_account(nick).is_none_or(|a| !a.eq_ignore_ascii_case(account)) {
         ctx.notice(me, from.uid, format!("\x02{nick}\x02 isn't grouped to your account."));
         return;
     }