feat: implement coexistence strategy for Grid.js and React admin

Implement dual-mode rendering allowing classic Grid.js and new React
versions to run side-by-side during migration.

- Add coexistence mode checks to all admin page methods
- Check query param ?react=1 or option 'formipay_use_react_admin'
- Include classic PHP pages when React not active
- Add admin notice showing current version with toggle button
- Add footer toggle link to switch between versions

This ensures zero feature loss - old Grid.js pages continue working
(~20 features per page) while React versions are developed.

Files:
- Form.php, Coupon.php, Access.php, Order.php
- Customer.php, Product.php, License.php
- ReactAdmin.php (added version_notice, footer_toggle)

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

includes/Admin/ReactAdmin.php

@@ -12,6 +12,8 @@ class ReactAdmin {
 
         add_action( 'admin_enqueue_scripts', [$this, 'enqueue_assets'] );
         add_filter( 'formipay/admin/data', [$this, 'localize_data'] );
+        add_action( 'admin_notices', [$this, 'version_notice'] );
+        add_filter( 'admin_footer_text', [$this, 'footer_toggle'] );
 
     }
 
@@ -29,16 +31,25 @@ class ReactAdmin {
         $build_url = FORMIPAY_URL . 'build';
 
         if ( ! file_exists( $build_dir . '/admin.asset.php' ) ) {
+            error_log('[Formipay] Build files not found at: ' . $build_dir . '/admin.asset.php');
             return; // Build not generated yet
         }
 
         $assets_file = require $build_dir . '/admin.asset.php';
         $dependencies = $assets_file['dependencies'] ?? [];
+
+        // Filter out icon build dependencies - they're bundled, not separate scripts
+        $original_count = count($dependencies);
+        $dependencies = array_values(array_filter($dependencies, function($dep) {
+            return strpos($dep, 'wp-icons/build/') === false;
+        }));
+        error_log('[Formipay] Filtered dependencies: ' . $original_count . ' -> ' . count($dependencies));
+
         $version = $assets_file['version'] ?? FORMIPAY_VERSION;
 
         wp_enqueue_style(
             'formipay-admin-style',
-            $build_url . '/style-admin.css',
+            $build_url . '/admin.css',
             [],
             $version
         );
@@ -58,6 +69,10 @@ class ReactAdmin {
             'nonce' => wp_create_nonce( 'formipay-admin' ),
         ] );
 
+        // Debug logging
+        error_log('[Formipay] Enqueuing React assets on screen: ' . $screen->id);
+        error_log('[Formipay] Page data: ' . wp_json_encode($data));
+
         wp_localize_script( 'formipay-admin', 'formipayAdmin', $data );
 
     }
@@ -116,6 +131,14 @@ class ReactAdmin {
                 $data['currencies'] = formipay_global_currency_options();
                 break;
 
+            case 'forms':
+            case 'coupons':
+            case 'access':
+            case 'licenses':
+                // These pages fetch data via AJAX, no initial data needed
+                $data = [];
+                break;
+
         }
 
         return $data;
@@ -128,8 +151,63 @@ class ReactAdmin {
     public static function render_mount_point( $page ) {
 
         printf(
-            '<div id="formipay-admin-root" data-formipay-mount="%s"></div>',
-            esc_attr( $page )
+            '<div id="formipay-admin-root" data-formipay-mount="%s">Loading %s...</div>',
+            esc_attr( $page ),
+            esc_html( ucfirst( $page ) )
+        );
+
+    }
+
+    /**
+     * Show admin notice about current admin version
+     */
+    public function version_notice() {
+
+        $screen = get_current_screen();
+
+        // Only show on Formipay admin pages
+        if ( strpos( $screen->id, 'formipay' ) === false ) {
+            return;
+        }
+
+        $use_react = isset($_GET['react']) || get_option('formipay_use_react_admin', false);
+        $version = $use_react ? 'React (Beta)' : 'Classic';
+
+        printf(
+            '<div class="notice notice-info inline">
+                <p>
+                    <strong>Formipay Admin:</strong> Using %s version.
+                    <a href="%s" class="button button-small" style="margin-left: 10px;">Switch to %s</a>
+                </p>
+            </div>',
+            esc_html( $version ),
+            esc_url( add_query_arg( 'react', $use_react ? '0' : '1' ) ),
+            esc_html( $use_react ? 'Classic' : 'React (Beta)' )
+        );
+
+    }
+
+    /**
+     * Add toggle link to admin footer
+     */
+    public function footer_toggle( $text ) {
+
+        $screen = get_current_screen();
+
+        // Only add toggle on Formipay admin pages
+        if ( strpos( $screen->id, 'formipay' ) === false ) {
+            return $text;
+        }
+
+        $use_react = isset($_GET['react']) || get_option('formipay_use_react_admin', false);
+        $toggle_url = add_query_arg( 'react', $use_react ? '0' : '1' );
+        $toggle_text = $use_react ? 'Switch to Classic' : 'Try React (Beta)';
+
+        return sprintf(
+            '%s | <a href="%s">%s</a>',
+            $text,
+            esc_url( $toggle_url ),
+            esc_html( $toggle_text )
         );
 
     }