refactor: extract navbar and footer into reusable handlebars partials

- Replace duplicated navbar markup across all HTML pages with {{> navbar }} partial
- Replace duplicated footer markup across all HTML pages with {{> footer }} partial
- Add TypeScript type definitions for vite-plugin-handlebars integration
- Update vite.config.ts to support handlebars partial compilation
- Update tsconfig.json to include handlebars type definitions
- Update nginx.conf for proper static file serving with partials
- Update translation files for de, pt, tr, vi, and zh-TW locales
- Reduce code duplication and improve maintainability across 13+ HTML pages
- Ensure consistent navbar and footer behavior across the entire application

nginx.conf

@@ -26,7 +26,7 @@ http {
         root /usr/share/nginx/html;
         index index.html;
         
-        rewrite ^/(en|de|zh|zh-TW|vi|it|tr|id|fr)/(.*)$ /$2 last;
+        rewrite ^/(en|de|zh|zh-TW|vi|it|tr|id|fr|pt)/(.*)$ /$2 last;
 
         location ~* \.html$ {
             expires 1h;