refactor: remove coexistence mode, use React only

Remove all dual-mode rendering logic since React is now the single
admin interface. Focus on implementing full table features in React.

Changes:
- Remove ?react= query param checks from all page methods
- Remove admin notice and footer toggle from ReactAdmin
- Simplify asset loading - ReactAdmin handles all assets
- Clean up Init.php enqueue method

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

includes/Order.php

@@ -644,39 +644,17 @@ class Order {
         $order_id = isset($_GET['order_id']) ? intval($_GET['order_id']) : 0;
         $page = $order_id ? 'order-detail' : 'orders';
 
-        // Coexistence mode: check query param or setting for React version
-        $use_react = isset($_GET['react']) || get_option('formipay_use_react_admin', false);
-
-        if ($use_react) {
-            // New React version
-            printf(
-                '<div id="formipay-admin-root" data-formipay-mount="%s"></div>',
-                esc_attr($page)
-            );
-        } else {
-            // Classic Grid.js version
-            if ($order_id) {
-                include_once FORMIPAY_PATH . 'admin/page-order-details.php';
-            } else {
-                include_once FORMIPAY_PATH . 'admin/page-orders.php';
-            }
-        }
+        // React admin
+        printf(
+            '<div id="formipay-admin-root" data-formipay-mount="%s"></div>',
+            esc_attr($page)
+        );
 
     }
 
     public function enqueue() {
-        global $current_screen;
-        if (!$current_screen) return;
-
-        // Check coexistence mode - if React is active, don't load classic assets
-        $use_react = isset($_GET['react']) || get_option('formipay_use_react_admin', false);
-        if ($use_react) {
-            return;
-        }
-
-        // Classic Grid.js assets would be loaded here
-        // (Original enqueue code was commented out, may need restoration)
-    }
+        // Assets now handled by ReactAdmin class
+        return;
 
     public function formipay_get_all_forms() {