fix: prevent asset conflicts between React and Grid.js versions

Add coexistence checks to all enqueue methods to prevent loading
both React and Grid.js assets simultaneously.

Changes:
- ReactAdmin.php: Only enqueue React assets when ?react=1
- Init.php: Skip Grid.js when React active on admin pages
- Form.php, Coupon.php, Access.php: Restore classic assets when ?react=0
- Customer.php, Product.php, License.php: Add coexistence checks

Now the toggle between Classic and React versions works correctly.

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

node_modules/@pmmmwh/react-refresh-webpack-plugin/loader/utils/normalizeOptions.js

@@ -0,0 +1,25 @@
+const { d, n } = require('../../options');
+
+/**
+ * Normalizes the options for the loader.
+ * @param {import('../types').ReactRefreshLoaderOptions} options Non-normalized loader options.
+ * @returns {import('../types').NormalizedLoaderOptions} Normalized loader options.
+ */
+const normalizeOptions = (options) => {
+  d(options, 'const', false);
+
+  n(options, 'esModule', (esModule) => {
+    if (typeof esModule === 'boolean' || typeof esModule === 'undefined') {
+      return esModule;
+    }
+
+    d(esModule, 'include');
+    d(esModule, 'exclude');
+
+    return esModule;
+  });
+
+  return options;
+};
+
+module.exports = normalizeOptions;