Fix(button): Prevent WooCommerce notices leaking during cart simulation

WooCommerce stores notices in the global session, not on the cart instance.
During PayPal cart simulation, `add_to_cart()` may trigger notices (e.g. "Please choose product options")
which then persist and are shown to the user.

This change snapshots existing notices before simulation and restores them afterward,
ensuring simulation-generated notices do not leak into the user session while preserving
legitimate notices.

Author: Narek13

modules/ppcp-button/src/Helper/IsolatedCartSimulator.php

@@ -44,6 +44,7 @@ public function simulate( array $products ): array {
 		};
 
 		add_filter( 'woocommerce_paypal_payments_is_simulating_cart', $simulation_filter );
+		$existing_notices = wc_get_notices();
 
 		try {
 			$cart = $this->create_isolated_cart();
@@ -62,6 +63,15 @@ public function simulate( array $products ): array {
 			throw $e;
 		} finally {
 			remove_filter( 'woocommerce_paypal_payments_is_simulating_cart', $simulation_filter );
+			$current_notices = wc_get_notices();
+
+			/**
+			 * Simulation may add WooCommerce notices (stored in the global session, not the cart).
+			 * Snapshot + restore ensures simulation notices don't leak into the user session.
+			 */
+			if ( $current_notices !== $existing_notices ) {
+				wc_set_notices( $existing_notices );
+			}
 
 			if ( $cart instanceof WC_Cart ) {
 				$this->cleanup_cart( $cart );