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/i18n.js

@@ -13,7 +13,7 @@ let currentLocale =
 
 // Supported locales (languages that have locale files on the server)
 // When a locale file is not found, the system gracefully falls back to English
-const supportedLocales = ['en', 'es', 'zh', 'fa'];
+const supportedLocales = ['en', 'es', 'zh', 'fa', 'fr', 'de', 'pt'];
 
 // Fallback to English if locale is not supported
 if (!supportedLocales.includes(currentLocale)) {