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/observable/race.js

@@ -0,0 +1,25 @@
+import { Observable } from '../Observable';
+import { innerFrom } from './innerFrom';
+import { argsOrArgArray } from '../util/argsOrArgArray';
+import { createOperatorSubscriber } from '../operators/OperatorSubscriber';
+export function race(...sources) {
+    sources = argsOrArgArray(sources);
+    return sources.length === 1 ? innerFrom(sources[0]) : new Observable(raceInit(sources));
+}
+export function raceInit(sources) {
+    return (subscriber) => {
+        let subscriptions = [];
+        for (let i = 0; subscriptions && !subscriber.closed && i < sources.length; i++) {
+            subscriptions.push(innerFrom(sources[i]).subscribe(createOperatorSubscriber(subscriber, (value) => {
+                if (subscriptions) {
+                    for (let s = 0; s < subscriptions.length; s++) {
+                        s !== i && subscriptions[s].unsubscribe();
+                    }
+                    subscriptions = null;
+                }
+                subscriber.next(value);
+            })));
+        }
+    };
+}
+//# sourceMappingURL=race.js.map