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/delegate/src/closest.js

@@ -0,0 +1,33 @@
+var DOCUMENT_NODE_TYPE = 9;
+
+/**
+ * A polyfill for Element.matches()
+ */
+if (typeof Element !== 'undefined' && !Element.prototype.matches) {
+    var proto = Element.prototype;
+
+    proto.matches = proto.matchesSelector ||
+                    proto.mozMatchesSelector ||
+                    proto.msMatchesSelector ||
+                    proto.oMatchesSelector ||
+                    proto.webkitMatchesSelector;
+}
+
+/**
+ * Finds the closest parent that matches a selector.
+ *
+ * @param {Element} element
+ * @param {String} selector
+ * @return {Function}
+ */
+function closest (element, selector) {
+    while (element && element.nodeType !== DOCUMENT_NODE_TYPE) {
+        if (typeof element.matches === 'function' &&
+            element.matches(selector)) {
+          return element;
+        }
+        element = element.parentNode;
+    }
+}
+
+module.exports = closest;

node_modules/delegate/src/delegate.js

@@ -0,0 +1,78 @@
+var closest = require('./closest');
+
+/**
+ * Delegates event to a selector.
+ *
+ * @param {Element} element
+ * @param {String} selector
+ * @param {String} type
+ * @param {Function} callback
+ * @param {Boolean} useCapture
+ * @return {Object}
+ */
+function _delegate(element, selector, type, callback, useCapture) {
+    var listenerFn = listener.apply(this, arguments);
+
+    element.addEventListener(type, listenerFn, useCapture);
+
+    return {
+        destroy: function() {
+            element.removeEventListener(type, listenerFn, useCapture);
+        }
+    }
+}
+
+/**
+ * Delegates event to a selector.
+ *
+ * @param {Element|String|Array} [elements]
+ * @param {String} selector
+ * @param {String} type
+ * @param {Function} callback
+ * @param {Boolean} useCapture
+ * @return {Object}
+ */
+function delegate(elements, selector, type, callback, useCapture) {
+    // Handle the regular Element usage
+    if (typeof elements.addEventListener === 'function') {
+        return _delegate.apply(null, arguments);
+    }
+
+    // Handle Element-less usage, it defaults to global delegation
+    if (typeof type === 'function') {
+        // Use `document` as the first parameter, then apply arguments
+        // This is a short way to .unshift `arguments` without running into deoptimizations
+        return _delegate.bind(null, document).apply(null, arguments);
+    }
+
+    // Handle Selector-based usage
+    if (typeof elements === 'string') {
+        elements = document.querySelectorAll(elements);
+    }
+
+    // Handle Array-like based usage
+    return Array.prototype.map.call(elements, function (element) {
+        return _delegate(element, selector, type, callback, useCapture);
+    });
+}
+
+/**
+ * Finds closest match and invokes callback.
+ *
+ * @param {Element} element
+ * @param {String} selector
+ * @param {String} type
+ * @param {Function} callback
+ * @return {Function}
+ */
+function listener(element, selector, type, callback) {
+    return function(e) {
+        e.delegateTarget = closest(e.target, selector);
+
+        if (e.delegateTarget) {
+            callback.call(element, e);
+        }
+    }
+}
+
+module.exports = delegate;