feat: Add Saleor webhook handler with Resend email integration

- Add Resend SDK for transactional emails
- Create React Email templates for order events:
  - OrderConfirmation
  - OrderShipped
  - OrderCancelled
  - OrderPaid
- Multi-language support (SR, EN, DE, FR)
- Customer emails in their language
- Admin emails in English to me@hytham.me and tamara@hytham.me
- Webhook handler at /api/webhooks/saleor
- Supports: ORDER_CONFIRMED, ORDER_FULLY_PAID, ORDER_CANCELLED, ORDER_FULFILLED
- Add GraphQL mutation to create webhooks in Saleor
- Add Resend API key to .env.local

src/emails/index.ts

@@ -0,0 +1,5 @@
+export { BaseLayout } from "./BaseLayout";
+export { OrderConfirmation } from "./OrderConfirmation";
+export { OrderShipped } from "./OrderShipped";
+export { OrderCancelled } from "./OrderCancelled";
+export { OrderPaid } from "./OrderPaid";