Add German and Swedish translations

Added de.json and sv.json locale files for German and Swedish language support. Updated i18n.js to register 'de' and 'sv' as available languages in the launcher.

GUI/js/i18n.js

@@ -5,6 +5,8 @@ const i18n = (() => {
   const availableLanguages = [
     { code: 'en', name: 'English' },
     { code: 'fr', name: 'Français' },
+    { code: 'de', name: 'Deutsch' },
+    { code: 'sv', name: 'Svenska' },
     { code: 'es-ES', name: 'Español (España)' },
     { code: 'pt-BR', name: 'Portuguese (Brazil)' },
     { code: 'tr-TR', name: 'Turkish (Turkey)' },