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/common/src/config/network.rs

@@ -190,7 +190,7 @@ impl Network {
             }),
             info: Info {
                 provider: Provider {
-                    name: "Stalwart".into(),
+                    name: types::brand!().into(),
                     ..Default::default()
                 },
                 ..Default::default()