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/rxjs/dist/esm/internal/testing/ColdObservable.js

@@ -0,0 +1,34 @@
+import { Observable } from '../Observable';
+import { Subscription } from '../Subscription';
+import { SubscriptionLoggable } from './SubscriptionLoggable';
+import { applyMixins } from '../util/applyMixins';
+import { observeNotification } from '../Notification';
+export class ColdObservable extends Observable {
+    constructor(messages, scheduler) {
+        super(function (subscriber) {
+            const observable = this;
+            const index = observable.logSubscribedFrame();
+            const subscription = new Subscription();
+            subscription.add(new Subscription(() => {
+                observable.logUnsubscribedFrame(index);
+            }));
+            observable.scheduleMessages(subscriber);
+            return subscription;
+        });
+        this.messages = messages;
+        this.subscriptions = [];
+        this.scheduler = scheduler;
+    }
+    scheduleMessages(subscriber) {
+        const messagesLength = this.messages.length;
+        for (let i = 0; i < messagesLength; i++) {
+            const message = this.messages[i];
+            subscriber.add(this.scheduler.schedule((state) => {
+                const { message: { notification }, subscriber: destination } = state;
+                observeNotification(notification, destination);
+            }, message.frame, { message, subscriber }));
+        }
+    }
+}
+applyMixins(ColdObservable, [SubscriptionLoggable]);
+//# sourceMappingURL=ColdObservable.js.map