feat: add Portuguese (PT-BR) translation (#132)

- Add pt.js translation file with complete PT-BR translations
- Add Portuguese option to language selector in settings
- Load pt.js translation file in index.html

Based on PR #108

Co-authored-by: Pedro Farias <feliperodriguesf62@gmail.com>
Co-authored-by: Wha1eChai <whaleora@gmail.com>

public/views/settings.html

@@ -79,6 +79,7 @@
                             <option value="zh">中文</option>
                             <option value="tr">Türkçe</option>
                             <option value="id">Bahasa Indonesia</option>
+                            <option value="pt">Português (BR)</option>
                         </select>
                     </div>