feat: add admin/profile UI, i18n (fr/de/pt), fix CI pipelines

- Add admin panel link and profile modal in user menu dropdown
- Add French, German and Portuguese locale support (full translations)
- Register new locales across JS frontend and Rust backend
- Create CI pipeline (fmt, clippy, test, audit, build)
- Fix docker-build.yml (cache, real tests, reduced timeout)
- Fix docker-publish.yml (multi-arch via QEMU, latest tag, pre-publish tests)
- Add dependabot.yml for automated dependency updates

static/js/languageSelector.js

@@ -13,7 +13,10 @@ function getAvailableLanguages() {
         { code: 'en', name: 'English', flag: '🇬🇧' },
         { code: 'es', name: 'Español', flag: '🇪🇸' },
         { code: 'zh', name: '中文', flag: '🇨🇳' },
-        { code: 'fa', name: 'فارسی', flag: '🇮🇷' }
+        { code: 'fa', name: 'فارسی', flag: '🇮🇷' },
+        { code: 'fr', name: 'Français', flag: '🇫🇷' },
+        { code: 'de', name: 'Deutsch', flag: '🇩🇪' },
+        { code: 'pt', name: 'Português', flag: '🇧🇷' }
     ];
 }