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/requestidlecallback/test/index.html

@@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<html>
+<head>
+	<meta charset="utf-8">
+	<title>Mocha Tests</title>
+	<link rel="stylesheet" href="../node_modules/mocha/mocha.css" />
+</head>
+<body>
+<div id="mocha"></div>
+<script src="../node_modules/mocha/mocha.js"></script>
+<script src="../node_modules/chai/chai.js"></script>
+<script src="../node_modules/sinon/pkg/sinon.js"></script>
+<script>mocha.setup('tdd')</script>
+<script src="../index.js"></script>
+<script src="test.js"></script>
+<script>
+	mocha.checkLeaks();
+	if (window.mochaPhantomJS) mochaPhantomJS.run();
+	else mocha.run();
+</script>
+</body>
+</html>

node_modules/requestidlecallback/test/test.js

@@ -0,0 +1,113 @@
+suite('idleCallbackShim', function() {
+	test('should have api methods', function(){
+		chai.assert(idleCallbackShim.request);
+		chai.assert(idleCallbackShim.cancel);
+	});
+
+	test('should invoke callback async', function(done){
+		var isRun = false;
+		var callback = sinon.spy();
+		var timeoutCall = sinon.spy();
+		var run = function(){
+			if(isRun){return;}
+			isRun = true;
+			chai.assert(timeoutCall.calledBefore(callback));
+			done();
+		};
+
+		idleCallbackShim.request(callback);
+		setTimeout(timeoutCall, 0);
+
+		idleCallbackShim.request(run);
+		setTimeout(run, 999);
+	});
+
+	test('should schedule nested callback later', function(done){
+		idleCallbackShim.request(function(){
+			var isRun = false;
+			var callback = sinon.spy();
+			var timeoutCall = sinon.spy();
+			var run = function(){
+				if(isRun){return;}
+				isRun = true;
+				chai.assert(timeoutCall.calledBefore(callback));
+				done();
+			};
+
+			idleCallbackShim.request(callback);
+			setTimeout(timeoutCall, 0);
+
+			idleCallbackShim.request(run);
+			setTimeout(run, 999);
+		});
+	});
+
+	test('should invoke with the deadline argument', function(done){
+		idleCallbackShim.request(function(deadline){
+			chai.assert('didTimeout' in deadline);
+			chai.assert(!deadline.didTimeout);
+			try {
+				deadline.didTimeout = true;
+			} catch(e){}
+			chai.assert(!deadline.didTimeout);
+
+			chai.assert(typeof deadline.timeRemaining() == 'number');
+			chai.assert(deadline.timeRemaining() >= 0 && deadline.timeRemaining() <= 50);
+			done();
+		});
+	});
+
+	test('timeRemaining counts down', function(done){
+		idleCallbackShim.request(function(deadline){
+			var now = Date.now();
+			var timeRemaining = deadline.timeRemaining();
+			while(Date.now() - now <= 2){
+
+			}
+			chai.assert(timeRemaining > deadline.timeRemaining());
+			done();
+		});
+	});
+
+	test('cancels callback', function(done){
+		var canceledID1, canceledID2, canceledID3;
+		var run1 = sinon.spy();
+		var run2 = sinon.spy();
+		var run3 = sinon.spy();
+		var canceled1 = sinon.spy();
+		var canceled2 = sinon.spy();
+		var canceled3 = sinon.spy();
+
+		idleCallbackShim.request(run1);
+		canceledID1 = idleCallbackShim.request(canceled1);
+
+
+		idleCallbackShim.request(function(){
+			idleCallbackShim.request(run3);
+			idleCallbackShim.cancel(canceledID2);
+
+			canceledID3 = idleCallbackShim.request(canceled3);
+
+			idleCallbackShim.cancel(canceledID3);
+
+			idleCallbackShim.request(function(){
+				chai.assert(run1.called);
+				chai.assert(run2.called);
+				chai.assert(run3.called);
+
+				chai.assert(!canceled1.called);
+				chai.assert(!canceled2.called);
+				chai.assert(!canceled3.called);
+				done();
+			});
+		});
+
+		idleCallbackShim.request(run2);
+		canceledID2 = idleCallbackShim.request(canceled2);
+
+
+		setTimeout(function(){
+			idleCallbackShim.cancel(canceledID1);
+		});
+	});
+});