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/vary/HISTORY.md

@@ -0,0 +1,39 @@
+1.1.2 / 2017-09-23
+==================
+
+  * perf: improve header token parsing speed
+
+1.1.1 / 2017-03-20
+==================
+
+  * perf: hoist regular expression
+
+1.1.0 / 2015-09-29
+==================
+
+  * Only accept valid field names in the `field` argument
+    - Ensures the resulting string is a valid HTTP header value
+
+1.0.1 / 2015-07-08
+==================
+
+  * Fix setting empty header from empty `field`
+  * perf: enable strict mode
+  * perf: remove argument reassignments
+
+1.0.0 / 2014-08-10
+==================
+
+  * Accept valid `Vary` header string as `field`
+  * Add `vary.append` for low-level string manipulation
+  * Move to `jshttp` orgainzation
+
+0.1.0 / 2014-06-05
+==================
+
+  * Support array of fields to set
+
+0.0.0 / 2014-06-04
+==================
+
+  * Initial release