fix: resolve all Week 1 critical bugs (F1.1–F1.9)

- Fix Customer::update() fatal error (undefined $table_name, $new_args)
- Fix Order::delete() using wrong variable $id instead of $order_id
- Fix Order::bulk_delete() using outer $order_id instead of loop $id
- Fix Email::send_email() calling non-existent class (use parent::)
- Add missing Order import in Paypal.php
- Fix BankTransfer unique_code triple DB call (call once, reuse result)
- Fix color field label showing "Number" instead of "Color"
- Add nonce verification to Customer::formipay_tabledata_customers()

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

includes/Order.php

@@ -914,7 +914,7 @@ class Order {
 
 		return $wpdb->delete(
 			$wpdb->prefix . 'formipay_orders',
-			['id' => $id],
+			['id' => $order_id],
 			['%d'],
 		);
 
@@ -1067,7 +1067,7 @@ class Order {
         $report = __( 'Done.', 'formipay' );
         if(!empty($ids)){
             foreach($ids as $id){
-                $delete = $this->delete($order_id);
+                $delete = $this->delete($id);
                 if(is_wp_error( $delete )){
                     $failed++;
                 }else{