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>

admin/assets/js/admin-customers.js

@@ -2,7 +2,7 @@ jQuery(function($){
 
     let formipay_table_grid = new gridjs.Grid({
         server: {
-            url: formipay_customers_page.ajax_url+'?action=formipay-tabledata-customers&limit='+document.getElementById('limit').value+'&keyword='+document.getElementById('keyword').value,
+            url: formipay_customers_page.ajax_url+'?action=formipay-tabledata-customers&_wpnonce='+formipay_customers_page.nonce+'&limit='+document.getElementById('limit').value+'&keyword='+document.getElementById('keyword').value,
             then: data => {
                 
                 // if(data.posts_report){
@@ -52,7 +52,7 @@ jQuery(function($){
     $('#limit, #keyword').on('change', function(){
         formipay_table_grid.updateConfig({
             server: {
-                url: formipay_customers_page.ajax_url+'?action=formipay-tabledata-customers&limit='+document.getElementById('limit').value+'&keyword='+document.getElementById('keyword').value,
+                url: formipay_customers_page.ajax_url+'?action=formipay-tabledata-customers&_wpnonce='+formipay_customers_page.nonce+'&limit='+document.getElementById('limit').value+'&keyword='+document.getElementById('keyword').value,
                 then: data => data.results.map(
                     form => [form.ID, form.name, form.email, form.phone, form.total_order]
                 ),