feat(emails): implement transactional email system with Resend

- Add Resend email integration with @react-email/render
- Create email templates: OrderConfirmation, OrderShipped, OrderCancelled, OrderPaid
- Implement webhook handler for ORDER_CREATED and other events
- Add multi-language support for customer emails
- Admin emails in English with order details
- Update checkout page with auto-scroll on order completion
- Configure DASHBOARD_URL environment variable

package.json

@@ -11,6 +11,7 @@
   "dependencies": {
     "@apollo/client": "^4.1.6",
     "@react-email/components": "^1.0.10",
+    "@react-email/render": "^2.0.4",
     "clsx": "^2.1.1",
     "framer-motion": "^12.34.4",
     "graphql": "^16.13.1",