About: name the webmail node and the mail server node

Settings > About shows which webmail node answered (NODE_NAME, else the
container hostname) and which inbuxa node it talks to: the address the
server's name resolves to from the webmail, named by its PTR record. The
server only tells administrators its node name, so the webmail works it
out itself. Fetched from /api/about/nodes on every visit, cached for a
minute server-side, for troubleshooting a cluster.

Fork-only: upstream ihasmail runs one webmail against one server.
4 new strings, translated in all 9 catalogues.

web/src/locales/pt-BR.ts

@@ -1716,6 +1716,11 @@ export const catalog: Catalog = {
     "To confirm, type {phrase}": "Para confirmar, digite {phrase}",
     "Turn off legacy protocols": "Desativar os protocolos de e-mail legados",
     "Legacy mail protocols are off for your organization. Only {app} and JMAP apps can sign in.": "Os protocolos de e-mail legados estão desativados para sua organização. Só {app} e aplicativos JMAP podem entrar.",
+    // ── About: webmail and mail server nodes (inbuxa) ──────────────
+    "Webmail node": "Nó do webmail",
+    "Mail server node": "Nó do servidor de e-mail",
+    "{host} does not resolve": "{host} não resolve",
+    "unavailable": "indisponível",
     // ── Spam filter: the language model's opinion (inbuxa) ──────────
     "Language model's opinion": "Opinião do modelo de linguagem",
     "One of several signals the spam filter weighed": "Um dos vários sinais considerados pelo filtro de spam",