Feat(i18n): promote Brazilian Portuguese to full locale status

- flip pt-BR to status:'full' in the locale registry
- add pt-BR boot-screen quips and slow hint to index.html, and list it
  in the JSON-LD inLanguage
- fill the productivity import-list name that landed after the pt-BR pack
- swap TRANSLATING.md's new-language walkthrough example to es-MX now
  that pt-BR is a real full locale

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

index.html

@@ -56,7 +56,7 @@
     "name": "IPCheck.ing",
     "url": "__SITE_URL__/",
     "description": "Open-source IP toolbox: lookup, connectivity tests, WebRTC and DNS leak detection, speed test, MTR, Whois, and browser fingerprint.",
-    "inLanguage": ["en", "zh-CN", "zh-TW", "fr", "ru"],
+    "inLanguage": ["en", "zh-CN", "zh-TW", "fr", "ru", "pt-BR"],
     "publisher": { "@type": "Person", "name": "Jason Ng" }
   }
   </script>
@@ -381,6 +381,16 @@
           'Спрашиваем у DNS, где вы на самом деле…',
           'Почти готово, честно…',
         ],
+        'pt-BR': [
+          'Instalando os drivers da placa de rede…',
+          'Alinhando o conector RJ45…',
+          'Conectando a fibra ao roteador…',
+          'Soprando a poeira da porta Ethernet…',
+          'Reiniciando o modem (tentativa nº 1)…',
+          'Triplo aperto de mão com seu provedor…',
+          'Perguntando ao DNS onde você realmente está…',
+          'Quase lá, prometemos…',
+        ],
       };
 
       // Slow-network hint (revealed after 12s by the head script). Stored as
@@ -392,6 +402,7 @@
         'zh-TW': '等太久了？試試 <a href="https://lite.ipcheck.ing/">IPCheck.ing Lite</a>，或重新整理頁面。',
         fr: 'C’est un peu long ? Essayez <a href="https://lite.ipcheck.ing/">IPCheck.ing Lite</a>, ou actualisez la page.',
         ru: 'Слишком долго? Попробуйте <a href="https://lite.ipcheck.ing/">IPCheck.ing Lite</a> или обновите страницу.',
+        'pt-BR': 'Esperando demais? Experimente o <a href="https://lite.ipcheck.ing/">IPCheck.ing Lite</a> ou atualize a página.',
       };
 
       // Hand-copy of matchLocale() in common/locale-registry.js — index.html