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.

tests/src/jmap/calendar/calendars.rs

@@ -43,7 +43,7 @@ pub async fn test(test: &TestServer) {
         list[0],
         json!({
             "id": default_calendar_id,
-            "name": "Stalwart Calendar ([email protected])",
+            "name": "INBUXA Calendar ([email protected])",
             "description": null,
             "sortOrder": 0,
             "isSubscribed": true,
@@ -308,7 +308,7 @@ pub async fn test(test: &TestServer) {
     }));
     response.list()[1].assert_is_equal(json!({
         "id": default_calendar_id,
-        "name": "Stalwart Calendar ([email protected])",
+        "name": "INBUXA Calendar ([email protected])",
         "description": (),
         "sortOrder": 0,
         "isSubscribed": true,