feat(notifications): add multi-channel notification module with Email, FCM, templates, and event listeners

- Domain: NotificationLog/NotificationPreference entities, repositories, channel value object
- Infrastructure: EmailService (nodemailer/SMTP), FcmService (firebase-admin), TemplateService (Handlebars)
- Application: SendNotification CQRS command, UserRegistered + AgentVerified event listeners
- Presentation: NotificationsController with history, preferences, and templates endpoints
- Prisma: NotificationLog and NotificationPreference models with proper indexes
- Templates: Vietnamese notification templates for user.registered, agent.verified, listing.approved, inquiry.received, password.reset

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/app/(auth)/layout.tsx

@@ -0,0 +1,7 @@
+export default function AuthLayout({ children }: { children: React.ReactNode }) {
+  return (
+    <div className="flex min-h-screen items-center justify-center bg-muted/40 px-4 py-12">
+      <div className="w-full max-w-md">{children}</div>
+    </div>
+  );
+}