Use the server's renamed registry capability, urn:inbuxa:jmap:registry

inbuxa-server renames the identifiers that carried the upstream name (its
SPEC.md §2.4). Upstream's capability for the registry (x:) objects is now
urn:inbuxa:jmap:registry, beside the fork's own urn:inbuxa:jmap, which is
unchanged. There's no alias, so this lands with the server change and
deploys with it. The mock advertises the new name too. No user-visible
strings change.

web/src/views/admin/__tests__/account-sheet.test.tsx

@@ -15,7 +15,7 @@ const HELPDESK = ["sysAccountGet", "sysAccountQuery", "sysAccountUpdate"];
 
 function signIn(permissions: string[], username = "[email protected]") {
   useSession.setState({
-    session: { capabilities: {}, accounts: {}, primaryAccounts: { "urn:stalwart:jmap": "self" }, username, ihasmail: { permissions } } as unknown as JmapSession,
+    session: { capabilities: {}, accounts: {}, primaryAccounts: { "urn:inbuxa:jmap:registry": "self" }, username, ihasmail: { permissions } } as unknown as JmapSession,
   });
 }