feat: implement header/footer visibility controls for checkout and thankyou pages

- Created LayoutWrapper component to conditionally render header/footer based on route
- Created MinimalHeader component (logo only)
- Created MinimalFooter component (trust badges + policy links)
- Created usePageVisibility hook to get visibility settings per page
- Wrapped ClassicLayout with LayoutWrapper for conditional rendering
- Header/footer visibility now controlled directly in React SPA
- Settings: show/minimal/hide for both header and footer
- Background color support for checkout and thankyou pages

includes/Api/CheckoutController.php

@@ -225,9 +225,8 @@ class CheckoutController {
         // Totals
         $order->calculate_totals();
 
-        // Mirror Woo hooks so extensions still work
+        // Mirror Woo hooks so extensions still work (but not thankyou which outputs HTML)
         do_action('woocommerce_checkout_create_order', $order->get_id(), $order);
-        do_action('woocommerce_thankyou', $order->get_id());
 
         $order->save();