feat(i18n): add Portuguese (Brazil) locale (pt-BR) (#6943)

Finalmente o idioma em Portugues do Brasil verá a luz do dia (se tudo
correr bem).

What has been done:

- Added pt-BR to .i18nrc.cjs and settings
- Included loaders in src/i18n.ts and apps/desktop-ui/src/i18n.ts
- Now Portuguese (BR) is displayed in the language selector
- Created empty main.json, commands.json, settings.json and
nodeDefs.json files to be populated by CI

- Checklist: the language appears in the dropdown list, selection occurs
without errors, the fallback to English, in case technical terms have no
translation, is working correctly.

- I will maintain the pt-br translation and review for as long as
necessary.

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Co-authored-by: Comfy Contributor <dev@example.com>

.i18nrc.cjs

@@ -9,7 +9,7 @@ module.exports = defineConfig({
   entry: 'src/locales/en',
   entryLocale: 'en',
   output: 'src/locales',
-  outputLocales: ['zh', 'zh-TW', 'ru', 'ja', 'ko', 'fr', 'es', 'ar', 'tr'],
+  outputLocales: ['zh', 'zh-TW', 'ru', 'ja', 'ko', 'fr', 'es', 'ar', 'tr', 'pt-BR'],
   reference: `Special names to keep untranslated: flux, photomaker, clip, vae, cfg, stable audio, stable cascade, stable zero, controlnet, lora, HiDream.
   'latent' is the short form of 'latent space'.
   'mask' is in the context of image processing.