Add internationalization (i18n) with next-intl and Italian translations

- Integrated `next-intl` for server-side and client-side i18n support.
- Added English (`en.json`) and Italian (`it.json`) localization files.
- Configured routing with locale-based subdirectories (`/[locale]/path`) using `next-intl`.
- Introduced type-safe i18n utilities and TypeScript definitions for translation keys.
- Updated middleware to handle locale detection and routing.
- Implemented dynamic translation loading to reduce bundle size.
- Enhanced developer experience with auto-complete and compile-time validation for i18n keys.

frontend/src/app/demos/page.tsx

@@ -16,7 +16,6 @@ import {
   LogIn,
   Settings,
   Users,
-  Lock,
   Activity,
   UserCog,
   BarChart3,