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/imap/src/op/capability.rs

@@ -68,8 +68,11 @@ impl<T: SessionStream> Session<T> {
                 .with_tag(request.tag)
                 .serialize(
                     concat!(
-                        "* ID (\"name\" \"Stalwart\" \"version\" \"1.0.0\" \"vendor\" \"Stalwart Labs LLC\" ",
-                        "\"support-url\" \"https://stalw.art\")\r\n"
+                        "* ID (\"name\" \"",
+                        types::brand!(),
+                        "\" \"version\" \"1.0.0\" \"vendor\" \"",
+                        types::brand!(),
+                        "\")\r\n"
                     )
                     .as_bytes()
                     .to_vec(),