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/fast-glob/out/utils/stream.js

@@ -0,0 +1,17 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.merge = void 0;
+const merge2 = require("merge2");
+function merge(streams) {
+    const mergedStream = merge2(streams);
+    streams.forEach((stream) => {
+        stream.once('error', (error) => mergedStream.emit('error', error));
+    });
+    mergedStream.once('close', () => propagateCloseEventToSources(streams));
+    mergedStream.once('end', () => propagateCloseEventToSources(streams));
+    return mergedStream;
+}
+exports.merge = merge;
+function propagateCloseEventToSources(streams) {
+    streams.forEach((stream) => stream.emit('close'));
+}