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/@wordpress/a11y/build/clear.js

@@ -0,0 +1,22 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = clear;
+/**
+ * Clears the a11y-speak-region elements and hides the explanatory text.
+ */
+function clear() {
+  const regions = document.getElementsByClassName('a11y-speak-region');
+  const introText = document.getElementById('a11y-speak-intro-text');
+  for (let i = 0; i < regions.length; i++) {
+    regions[i].textContent = '';
+  }
+
+  // Make sure the explanatory text is hidden from assistive technologies.
+  if (introText) {
+    introText.setAttribute('hidden', 'hidden');
+  }
+}
+//# sourceMappingURL=clear.js.map