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/directory/src/backend/oidc/config.rs

@@ -38,7 +38,7 @@ impl OpenIdDirectory {
 
     pub async fn new(config: OidcConfig) -> Result<Self, OidcError> {
         let http = utils::http::http_client_builder(false)
-            .user_agent("Stalwart/1.0")
+            .user_agent("INBUXA/1.0") // types::brand!(); this crate does not depend on types
             .timeout(Duration::from_secs(30))
             .build()
             .map_err(|e| OidcError::Network(format!("HTTP client build failed: {e}")))?;