feat(i18n): add Brazilian Portuguese locale (#8203)

Add the `pt` frontend and backend locale bundles, register the language in
the language selector, and add a Portuguese README linked from the other
READMEs.

Co-authored-by: Nicolas Pastorello <opastorello@MacBookPro.pastorello.infra>
Co-authored-by: Claude Sonnet 5.5 <noreply@anthropic.com>

src/components/setting/setting-verge-basic.tsx

@@ -44,6 +44,7 @@ const languageOptions = supportedLanguages.map((code) => {
     es: 'Español',
     jp: '日本語',
     zhtw: '繁體中文',
+    pt: 'Português',
   }
   const label = labels[code] || code
   return { code, label }