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/i18n/request.ts

@@ -0,0 +1,44 @@
+// src/i18n/request.ts
+/**
+ * Server-side i18n request configuration for next-intl.
+ *
+ * This file handles:
+ * - Loading translation messages for the requested locale
+ * - Server-side locale detection
+ * - Time zone configuration
+ *
+ * Important:
+ * - This runs on the server only (Next.js App Router)
+ * - Translation files are NOT sent to the client (zero bundle overhead)
+ * - Messages are loaded on-demand per request
+ */
+
+import { getRequestConfig } from 'next-intl/server';
+import { routing } from './routing';
+
+export default getRequestConfig(async ({ locale }) => {
+  // Validate that the incoming `locale` parameter is valid
+  // Type assertion: we know locale will be a string from the URL parameter
+  const requestedLocale = locale as 'en' | 'it';
+
+  // Check if the requested locale is supported, otherwise use default
+  const validLocale = routing.locales.includes(requestedLocale)
+    ? requestedLocale
+    : routing.defaultLocale;
+
+  return {
+    // Return the validated locale
+    locale: validLocale,
+
+    // Load messages for the requested locale
+    // Dynamic import ensures only the requested locale is loaded
+    messages: (await import(`../../messages/${validLocale}.json`)).default,
+
+    // Optional: Configure time zone
+    // This will be used for date/time formatting
+    // timeZone: 'Europe/Rome', // Example for Italian users
+
+    // Optional: Configure now (for relative time formatting)
+    // now: new Date(),
+  };
+});