Use the server's renamed registry capability and web interface client

inbuxa-server renames the identifiers that carried the upstream name
(its SPEC.md §2.4): upstream's JMAP capability for the registry (x:)
objects is urn:inbuxa:jmap:registry, beside the fork's own urn:inbuxa:jmap,
and the web interface it serves signs in as inbuxa-webui. There are no
aliases, so this lands with the server change and deploys with it.

src/services/jmap/client.ts

@@ -15,7 +15,7 @@ import type { Schema } from '@/types/schema';
 
 const JMAP_USING = [
   'urn:ietf:params:jmap:core',
-  'urn:stalwart:jmap',
+  'urn:inbuxa:jmap:registry',
   'urn:ietf:params:jmap:blob',
   'urn:ietf:params:jmap:mail',
   'urn:ietf:params:jmap:calendars',