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/docs/rules/no-jasmine-globals.md

@@ -0,0 +1,67 @@
+# Disallow Jasmine globals (`no-jasmine-globals`)
+
+💼 This rule is enabled in the ✅ `recommended`
+[config](https://github.com/jest-community/eslint-plugin-jest/blob/main/README.md#shareable-configurations).
+
+🔧 This rule is automatically fixable by the
+[`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).
+
+<!-- end auto-generated rule header -->
+
+`jest` uses `jasmine` as a test runner. A side effect of this is that both a
+`jasmine` object, and some jasmine-specific globals, are exposed to the test
+environment. Most functionality offered by Jasmine has been ported to Jest, and
+the Jasmine globals will stop working in the future. Developers should therefore
+migrate to Jest's documented API instead of relying on the undocumented Jasmine
+API.
+
+## Rule details
+
+This rule reports on any usage of Jasmine globals, which is not ported to Jest,
+and suggests alternatives from Jest's own API.
+
+## Examples
+
+The following patterns are considered warnings:
+
+```js
+jasmine.DEFAULT_TIMEOUT_INTERVAL = 5000;
+
+test('my test', () => {
+  pending();
+});
+
+test('my test', () => {
+  fail();
+});
+
+test('my test', () => {
+  spyOn(some, 'object');
+});
+
+test('my test', () => {
+  jasmine.createSpy();
+});
+
+test('my test', () => {
+  expect('foo').toEqual(jasmine.anything());
+});
+```
+
+The following patterns would not be considered warnings:
+
+```js
+jest.setTimeout(5000);
+
+test('my test', () => {
+  jest.spyOn(some, 'object');
+});
+
+test('my test', () => {
+  jest.fn();
+});
+
+test('my test', () => {
+  expect('foo').toEqual(expect.anything());
+});
+```