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/@pmmmwh/react-refresh-webpack-plugin/lib/utils/index.js

@@ -0,0 +1,19 @@
+const getAdditionalEntries = require('./getAdditionalEntries');
+const getIntegrationEntry = require('./getIntegrationEntry');
+const getRefreshGlobal = require('./getRefreshGlobal');
+const getSocketIntegration = require('./getSocketIntegration');
+const injectRefreshEntry = require('./injectRefreshEntry');
+const injectRefreshLoader = require('./injectRefreshLoader');
+const makeRefreshRuntimeModule = require('./makeRefreshRuntimeModule');
+const normalizeOptions = require('./normalizeOptions');
+
+module.exports = {
+  getAdditionalEntries,
+  getIntegrationEntry,
+  getRefreshGlobal,
+  getSocketIntegration,
+  injectRefreshEntry,
+  injectRefreshLoader,
+  makeRefreshRuntimeModule,
+  normalizeOptions,
+};