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/eslint/lib/rules/no-new-wrappers.js

@@ -0,0 +1,60 @@
+/**
+ * @fileoverview Rule to flag when using constructor for wrapper objects
+ * @author Ilya Volodin
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const { getVariableByName } = require("./utils/ast-utils");
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+/** @type {import('../shared/types').Rule} */
+module.exports = {
+    meta: {
+        type: "suggestion",
+
+        docs: {
+            description: "Disallow `new` operators with the `String`, `Number`, and `Boolean` objects",
+            recommended: false,
+            url: "https://eslint.org/docs/latest/rules/no-new-wrappers"
+        },
+
+        schema: [],
+
+        messages: {
+            noConstructor: "Do not use {{fn}} as a constructor."
+        }
+    },
+
+    create(context) {
+        const { sourceCode } = context;
+
+        return {
+
+            NewExpression(node) {
+                const wrapperObjects = ["String", "Number", "Boolean"];
+                const { name } = node.callee;
+
+                if (wrapperObjects.includes(name)) {
+                    const variable = getVariableByName(sourceCode.getScope(node), name);
+
+                    if (variable && variable.identifiers.length === 0) {
+                        context.report({
+                            node,
+                            messageId: "noConstructor",
+                            data: { fn: name }
+                        });
+                    }
+                }
+            }
+        };
+
+    }
+};