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-plugin-jest/lib/rules/no-conditional-in-test.js

@@ -0,0 +1,50 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = void 0;
+var _utils = require("./utils");
+var _default = exports.default = (0, _utils.createRule)({
+  name: __filename,
+  meta: {
+    docs: {
+      description: 'Disallow conditional logic in tests',
+      category: 'Best Practices',
+      recommended: false
+    },
+    messages: {
+      conditionalInTest: 'Avoid having conditionals in tests'
+    },
+    type: 'problem',
+    schema: []
+  },
+  defaultOptions: [],
+  create(context) {
+    let inTestCase = false;
+    const maybeReportConditional = node => {
+      if (inTestCase) {
+        context.report({
+          messageId: 'conditionalInTest',
+          node
+        });
+      }
+    };
+    return {
+      CallExpression(node) {
+        if ((0, _utils.isTypeOfJestFnCall)(node, context, ['test'])) {
+          inTestCase = true;
+        }
+      },
+      'CallExpression:exit'(node) {
+        if ((0, _utils.isTypeOfJestFnCall)(node, context, ['test'])) {
+          inTestCase = false;
+        }
+      },
+      IfStatement: maybeReportConditional,
+      SwitchStatement: maybeReportConditional,
+      ConditionalExpression: maybeReportConditional,
+      LogicalExpression: maybeReportConditional
+    };
+  }
+});