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/css-tree/cjs/lexer/trace.cjs

@@ -0,0 +1,73 @@
+'use strict';
+
+function getTrace(node) {
+    function shouldPutToTrace(syntax) {
+        if (syntax === null) {
+            return false;
+        }
+
+        return (
+            syntax.type === 'Type' ||
+            syntax.type === 'Property' ||
+            syntax.type === 'Keyword'
+        );
+    }
+
+    function hasMatch(matchNode) {
+        if (Array.isArray(matchNode.match)) {
+            // use for-loop for better perfomance
+            for (let i = 0; i < matchNode.match.length; i++) {
+                if (hasMatch(matchNode.match[i])) {
+                    if (shouldPutToTrace(matchNode.syntax)) {
+                        result.unshift(matchNode.syntax);
+                    }
+
+                    return true;
+                }
+            }
+        } else if (matchNode.node === node) {
+            result = shouldPutToTrace(matchNode.syntax)
+                ? [matchNode.syntax]
+                : [];
+
+            return true;
+        }
+
+        return false;
+    }
+
+    let result = null;
+
+    if (this.matched !== null) {
+        hasMatch(this.matched);
+    }
+
+    return result;
+}
+
+function isType(node, type) {
+    return testNode(this, node, match => match.type === 'Type' && match.name === type);
+}
+
+function isProperty(node, property) {
+    return testNode(this, node, match => match.type === 'Property' && match.name === property);
+}
+
+function isKeyword(node) {
+    return testNode(this, node, match => match.type === 'Keyword');
+}
+
+function testNode(match, node, fn) {
+    const trace = getTrace.call(match, node);
+
+    if (trace === null) {
+        return false;
+    }
+
+    return trace.some(fn);
+}
+
+exports.getTrace = getTrace;
+exports.isKeyword = isKeyword;
+exports.isProperty = isProperty;
+exports.isType = isType;