fix: Clear zone cache after toggle to force reload

Added aggressive cache clearing after toggle.

Issue:
- update_option saves to DB correctly
- But $method->enabled is loaded when zone object is created
- Zone object is cached, so it keeps old enabled value
- Next request loads cached zone with old enabled="yes"

Solution:
✅ Save instance_settings to DB
✅ Delete shipping method count transient
✅ Clear shipping_zones cache (all zones)
✅ Clear specific zone cache by ID
✅ Update $method->enabled in memory
✅ Clear global shipping cache version

This forces WooCommerce to:
1. Reload zone from database
2. Reload methods from database
3. Read fresh enabled value
4. Display correct state

Test: Toggle should now persist correctly

includes/Api/ShippingController.php

@@ -265,9 +265,8 @@ class ShippingController extends WP_REST_Controller {
 						isset( $method->instance_settings['enabled'] ) ? $method->instance_settings['enabled'] : 'not set'
 					) );
 
-					// Update BOTH the property AND the settings
+					// Update the settings array with new enabled value
 					$new_enabled_value = $enabled ? 'yes' : 'no';
-					$method->enabled = $new_enabled_value;
 					$method->instance_settings['enabled'] = $new_enabled_value;
 
 					// Debug: Log new state
@@ -278,6 +277,14 @@ class ShippingController extends WP_REST_Controller {
 					$saved = update_option( $option_key, $method->instance_settings, 'yes' );
 					error_log( sprintf( '[WooNooW] update_option(%s) returned: %s', $option_key, $saved ? 'true' : 'false' ) );
 					
+					// CRITICAL: Clear the zone's method cache so it reloads from DB
+					delete_transient( 'wc_shipping_method_count' );
+					wp_cache_delete( 'shipping_zones', 'woocommerce' );
+					wp_cache_delete( $zone_id, 'shipping_zones' );
+					
+					// Also update the in-memory property so WooCommerce sees it immediately
+					$method->enabled = $new_enabled_value;
+
 					// Fire action hook for other plugins/code
 					do_action( 'woocommerce_shipping_zone_method_status_toggled', $instance_id, $method->id, $zone_id, $enabled );