Refactor i18n integration and update tests for improved localization

- Updated test components (`PasswordResetConfirmForm`, `PasswordChangeForm`) to use i18n keys directly, ensuring accurate validation messages.
- Refined translations in `it.json` to standardize format and content.
- Replaced text-based labels with localized strings in `PasswordResetRequestForm` and `RegisterForm`.
- Introduced `generateLocalizedMetadata` utility and updated layout metadata generation for locale-aware SEO.
- Enhanced e2e tests with locale-prefixed routes and updated assertions for consistency.
- Added comprehensive i18n documentation (`I18N.md`) for usage, architecture, and testing.

frontend/src/app/[locale]/(auth)/login/page.tsx

@@ -1,4 +1,7 @@
+import { Metadata } from 'next';
 import dynamic from 'next/dynamic';
+import { generatePageMetadata, type Locale } from '@/lib/i18n/metadata';
+import { getTranslations } from 'next-intl/server';
 
 // Code-split LoginForm - heavy with react-hook-form + validation
 const LoginForm = dynamic(
@@ -15,6 +18,17 @@ const LoginForm = dynamic(
   }
 );
 
+export async function generateMetadata({
+  params,
+}: {
+  params: Promise<{ locale: string }>;
+}): Promise<Metadata> {
+  const { locale } = await params;
+  const t = await getTranslations({ locale, namespace: 'auth.login' });
+
+  return generatePageMetadata(locale as Locale, t('title'), t('subtitle'), '/login');
+}
+
 export default function LoginPage() {
   return (
     <div className="space-y-6">

frontend/src/app/[locale]/(auth)/password-reset/confirm/page.tsx

@@ -3,9 +3,28 @@
  * Users set a new password using the token from their email
  */
 
+import { Metadata } from 'next';
 import { Suspense } from 'react';
+import { generatePageMetadata, type Locale } from '@/lib/i18n/metadata';
+import { getTranslations } from 'next-intl/server';
 import PasswordResetConfirmContent from './PasswordResetConfirmContent';
 
+export async function generateMetadata({
+  params,
+}: {
+  params: Promise<{ locale: string }>;
+}): Promise<Metadata> {
+  const { locale } = await params;
+  const t = await getTranslations({ locale, namespace: 'auth.passwordResetConfirm' });
+
+  return generatePageMetadata(
+    locale as Locale,
+    t('title'),
+    t('instructions'),
+    '/password-reset/confirm'
+  );
+}
+
 export default function PasswordResetConfirmPage() {
   return (
     <Suspense

frontend/src/app/[locale]/(auth)/password-reset/page.tsx

@@ -3,7 +3,10 @@
  * Users enter their email to receive reset instructions
  */
 
+import { Metadata } from 'next';
 import dynamic from 'next/dynamic';
+import { generatePageMetadata, type Locale } from '@/lib/i18n/metadata';
+import { getTranslations } from 'next-intl/server';
 
 // Code-split PasswordResetRequestForm
 const PasswordResetRequestForm = dynamic(
@@ -22,6 +25,17 @@ const PasswordResetRequestForm = dynamic(
   }
 );
 
+export async function generateMetadata({
+  params,
+}: {
+  params: Promise<{ locale: string }>;
+}): Promise<Metadata> {
+  const { locale } = await params;
+  const t = await getTranslations({ locale, namespace: 'auth.passwordReset' });
+
+  return generatePageMetadata(locale as Locale, t('title'), t('subtitle'), '/password-reset');
+}
+
 export default function PasswordResetPage() {
   return (
     <div className="space-y-6">

frontend/src/app/[locale]/(auth)/register/page.tsx

@@ -1,4 +1,7 @@
+import { Metadata } from 'next';
 import dynamic from 'next/dynamic';
+import { generatePageMetadata, type Locale } from '@/lib/i18n/metadata';
+import { getTranslations } from 'next-intl/server';
 
 // Code-split RegisterForm (313 lines)
 const RegisterForm = dynamic(
@@ -15,6 +18,17 @@ const RegisterForm = dynamic(
   }
 );
 
+export async function generateMetadata({
+  params,
+}: {
+  params: Promise<{ locale: string }>;
+}): Promise<Metadata> {
+  const { locale } = await params;
+  const t = await getTranslations({ locale, namespace: 'auth.register' });
+
+  return generatePageMetadata(locale as Locale, t('title'), t('subtitle'), '/register');
+}
+
 export default function RegisterPage() {
   return (
     <div className="space-y-6">

frontend/src/app/[locale]/forbidden/page.tsx

@@ -3,16 +3,28 @@
  * Displayed when users try to access resources they don't have permission for
  */
 
-/* istanbul ignore next - Next.js type import for metadata */
 import type { Metadata } from 'next';
 import { Link } from '@/lib/i18n/routing';
 import { ShieldAlert } from 'lucide-react';
 import { Button } from '@/components/ui/button';
+import { generatePageMetadata, type Locale } from '@/lib/i18n/metadata';
+import { getTranslations } from 'next-intl/server';
 
-export const metadata: Metadata = /* istanbul ignore next */ {
-  title: '403 - Forbidden',
-  description: 'You do not have permission to access this resource',
-};
+export async function generateMetadata({
+  params,
+}: {
+  params: Promise<{ locale: string }>;
+}): Promise<Metadata> {
+  const { locale } = await params;
+  const t = await getTranslations({ locale, namespace: 'errors' });
+
+  return generatePageMetadata(
+    locale as Locale,
+    t('unauthorized'),
+    t('unauthorizedDescription'),
+    '/forbidden'
+  );
+}
 
 export default function ForbiddenPage() {
   return (

frontend/src/app/[locale]/layout.tsx

@@ -4,6 +4,7 @@ import { notFound } from 'next/navigation';
 import { routing } from '@/lib/i18n/routing';
 import { NextIntlClientProvider } from 'next-intl';
 import { getMessages } from 'next-intl/server';
+import { generateLocalizedMetadata, type Locale } from '@/lib/i18n/metadata';
 import '../globals.css';
 import { Providers } from '../providers';
 import { AuthProvider } from '@/lib/auth/AuthContext';
@@ -23,10 +24,14 @@ const geistMono = Geist_Mono({
   preload: false, // Only preload primary font
 });
 
-export const metadata: Metadata = {
-  title: 'FastNext Template',
-  description: 'FastAPI + Next.js Template',
-};
+export async function generateMetadata({
+  params,
+}: {
+  params: Promise<{ locale: string }>;
+}): Promise<Metadata> {
+  const { locale } = await params;
+  return generateLocalizedMetadata(locale as Locale);
+}
 
 export default async function LocaleLayout({
   children,

frontend/src/app/robots.ts

@@ -0,0 +1,21 @@
+import { MetadataRoute } from 'next';
+
+/**
+ * Generate robots.txt
+ * Configures search engine crawler behavior
+ */
+export default function robots(): MetadataRoute.Robots {
+  const baseUrl = process.env.NEXT_PUBLIC_SITE_URL || 'http://localhost:3000';
+
+  return {
+    rules: [
+      {
+        userAgent: '*',
+        allow: '/',
+        // Disallow authenticated routes
+        disallow: ['/admin/', '/settings/'],
+      },
+    ],
+    sitemap: `${baseUrl}/sitemap.xml`,
+  };
+}

frontend/src/app/sitemap.ts

@@ -0,0 +1,49 @@
+import { MetadataRoute } from 'next';
+import { routing } from '@/lib/i18n/routing';
+
+/**
+ * Generate multilingual sitemap
+ * Includes all public routes for each supported locale
+ */
+export default function sitemap(): MetadataRoute.Sitemap {
+  const baseUrl = process.env.NEXT_PUBLIC_SITE_URL || 'http://localhost:3000';
+
+  // Define public routes that should be in sitemap
+  const publicRoutes = [
+    '', // homepage
+    '/login',
+    '/register',
+    '/password-reset',
+    '/demos',
+    '/dev',
+    '/dev/components',
+    '/dev/layouts',
+    '/dev/forms',
+    '/dev/docs',
+  ];
+
+  // Generate sitemap entries for each locale
+  const sitemapEntries: MetadataRoute.Sitemap = [];
+
+  routing.locales.forEach((locale) => {
+    publicRoutes.forEach((route) => {
+      const path = route === '' ? `/${locale}` : `/${locale}${route}`;
+
+      sitemapEntries.push({
+        url: `${baseUrl}${path}`,
+        lastModified: new Date(),
+        changeFrequency: route === '' ? 'daily' : 'weekly',
+        priority: route === '' ? 1.0 : 0.8,
+        // Language alternates for this URL
+        alternates: {
+          languages: {
+            en: `${baseUrl}/en${route}`,
+            it: `${baseUrl}/it${route}`,
+          },
+        },
+      });
+    });
+  });
+
+  return sitemapEntries;
+}