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/enquirer/lib/completer.js

@@ -0,0 +1,52 @@
+'use strict';
+
+const unique = arr => arr.filter((v, i) => arr.lastIndexOf(v) === i);
+const compact = arr => unique(arr).filter(Boolean);
+
+module.exports = (action, data = {}, value = '') => {
+  let { past = [], present = '' } = data;
+  let rest, prev;
+
+  switch (action) {
+    case 'prev':
+    case 'undo':
+      rest = past.slice(0, past.length - 1);
+      prev = past[past.length - 1] || '';
+      return {
+        past: compact([value, ...rest]),
+        present: prev
+      };
+
+    case 'next':
+    case 'redo':
+      rest = past.slice(1);
+      prev = past[0] || '';
+      return {
+        past: compact([...rest, value]),
+        present: prev
+      };
+
+    case 'save':
+      return {
+        past: compact([...past, value]),
+        present: ''
+      };
+
+    case 'remove':
+      prev = compact(past.filter(v => v !== value));
+      present = '';
+
+      if (prev.length) {
+        present = prev.pop();
+      }
+
+      return {
+        past: prev,
+        present
+      };
+
+    default: {
+      throw new Error(`Invalid action: "${action}"`);
+    }
+  }
+};