Rebrand to INBUXA: product name, protocol greetings, sign-in page, calendar templates, logos, README

One branding module (types::brand!) supplies the name to every protocol
greeting, the HTTP realm, the startup banner, Received headers, the
user agent, the IMAP ID response and calendar PRODIDs. The sign-in and
calendar pages take ihasmail's palette and font and the INBUXA logo, and
calendar emails embed the INBUXA lockup. Default calendar and address book
names follow. Protocol identifiers (urn:stalwart:jmap, vnd.stalwart Sieve
extensions) and upstream copyright notices are unchanged.

crates/pop3/src/op/delete.rs

@@ -107,7 +107,8 @@ impl<T: SessionStream> Session<T> {
                 }
                 if not_deleted.is_empty() {
                     self.write_ok(format!(
-                        "Stalwart POP3 bids you farewell ({num_deleted} messages deleted)."
+                        concat!(types::brand!(), " POP3 bids you farewell ({} messages deleted)."),
+                        num_deleted
                     ))
                     .await?;
                 } else {
@@ -118,11 +119,11 @@ impl<T: SessionStream> Session<T> {
                     .await?;
                 }
             } else {
-                self.write_ok("Stalwart POP3 bids you farewell (no messages deleted).")
+                self.write_ok(concat!(types::brand!(), " POP3 bids you farewell (no messages deleted)."))
                     .await?;
             }
         } else {
-            self.write_ok("Stalwart POP3 bids you farewell.").await?;
+            self.write_ok(concat!(types::brand!(), " POP3 bids you farewell.")).await?;
         }
 
         trc::event!(