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/is-binary-path/index.d.ts

@@ -0,0 +1,17 @@
+/**
+Check if a file path is a binary file.
+
+@example
+```
+import isBinaryPath = require('is-binary-path');
+
+isBinaryPath('source/unicorn.png');
+//=> true
+
+isBinaryPath('source/unicorn.txt');
+//=> false
+```
+*/
+declare function isBinaryPath(filePath: string): boolean;
+
+export = isBinaryPath;