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/@sinonjs/commons/lib/every.js

@@ -0,0 +1,26 @@
+"use strict";
+
+/**
+ * Returns true when fn returns true for all members of obj.
+ * This is an every implementation that works for all iterables
+ * @param  {object}   obj
+ * @param  {Function} fn
+ * @returns {boolean}
+ */
+module.exports = function every(obj, fn) {
+    var pass = true;
+
+    try {
+        // eslint-disable-next-line @sinonjs/no-prototype-methods/no-prototype-methods
+        obj.forEach(function () {
+            if (!fn.apply(this, arguments)) {
+                // Throwing an error is the only way to break `forEach`
+                throw new Error();
+            }
+        });
+    } catch (e) {
+        pass = false;
+    }
+
+    return pass;
+};