add more comprehensive docs on cart display for pre purchase checkout pages

Author: masmalsah

docs/campaign-cart/cart-system/index.md

@@ -518,5 +518,6 @@ next.on('cart:item-removed', (data) => {
 
 ## Related Documentation
 
+- [Cart Summary Checkout](/docs/campaign-cart/guides/cart-summary-checkout) - Full cart and item attributes reference with checkout example
 - [Cart Attributes](/docs/campaign-cart/data-attributes/display/#cart-summary) - Display cart data
 - [Upsells](/docs/campaign-cart/upsells/) - Post-purchase flows

docs/campaign-cart/data-attributes/configuration.md

@@ -1032,6 +1032,7 @@ General utility attributes for common scenarios.
 
 ## Related Documentation
 
+- [Cart Summary Checkout](/docs/campaign-cart/guides/cart-summary-checkout) - Full cart and item attributes reference with checkout example
 - [Display Attributes](/docs/campaign-cart/data-attributes/display/) - Dynamic data display
 - [Action Attributes](/docs/campaign-cart/data-attributes/actions/) - Interactive elements
 - [State Attributes](/docs/campaign-cart/data-attributes/state/) - Conditional logic

docs/campaign-cart/data-attributes/display.md

@@ -284,6 +284,8 @@ Timer format options:
 </div>
 ```
 
+For a complete list of cart and item attributes plus a full checkout summary example, see [Cart Summary Checkout](/docs/campaign-cart/guides/cart-summary-checkout).
+
 ### Product Card with Dynamic Pricing
 
 ```html
@@ -976,6 +978,7 @@ Enable debug mode to see:
 
 ## Related Documentation
 
+- [Cart Summary Checkout](/docs/campaign-cart/guides/cart-summary-checkout) - Full cart and item attributes reference with checkout example
 - [Actions](/docs/campaign-cart/data-attributes/actions/) - Interactive elements
 - [State Management](/docs/campaign-cart/data-attributes/state/) - Conditional logic
 - [Events](/docs/campaign-cart/javascript-api/events/) - React to data changes

docs/campaign-cart/data-attributes/index.md

@@ -306,6 +306,7 @@ Always provide fallback content for progressive enhancement:
 
 ## Related Documentation
 
+- [Cart Summary Checkout](/docs/campaign-cart/guides/cart-summary-checkout) - Full cart and item attributes reference with checkout example
 - [JavaScript API](/docs/campaign-cart/javascript-api/) - JavaScript methods reference
 - [Events](/docs/campaign-cart/javascript-api/events/) - Responding to SDK events
 - [CSS Classes](/docs/campaign-cart/data-attributes/css-classes/) - Styling enhanced elements

docs/campaign-cart/data-attributes/state.md

@@ -546,6 +546,7 @@ await next.addItem({ packageId: 123 });
 
 ## Related Documentation
 
+- [Cart Summary Checkout](/docs/campaign-cart/guides/cart-summary-checkout) - Full cart and item attributes reference with checkout example
 - [Display Attributes](/docs/campaign-cart/data-attributes/display/) - Showing dynamic data
 - [Action Attributes](/docs/campaign-cart/data-attributes/actions/) - Interactive elements
 - [CSS Classes](/docs/campaign-cart/data-attributes/css-classes/) - Styling state classes