feat: complete saleor core extensions app with React email templates

- Order confirmation, shipped, and cancelled email templates
- Uses @react-email/components for professional HTML emails
- Sends admin and customer notifications
- Integrates with Resend for email delivery
- Webhook handlers for ORDER_CREATED, ORDER_FULFILLED, ORDER_CANCELLED
- Docker image optimized for production
- Persistent auth data storage via PVC

.eslintrc

@@ -0,0 +1,12 @@
+{
+  "extends": ["next", "plugin:@saleor/saleor-app/recommended", "prettier"],
+  "plugins": ["simple-import-sort"],
+  "parserOptions": {
+    "project": "tsconfig.json"
+  },
+  "rules": {
+    "import/order": "off", // to avoid conflicts with simple-import-sort
+    "simple-import-sort/imports": "warn",
+    "simple-import-sort/exports": "warn"
+  }
+}