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/framer-motion/dist/es/utils/array.mjs

@@ -0,0 +1,21 @@
+function addUniqueItem(arr, item) {
+    if (arr.indexOf(item) === -1)
+        arr.push(item);
+}
+function removeItem(arr, item) {
+    const index = arr.indexOf(item);
+    if (index > -1)
+        arr.splice(index, 1);
+}
+// Adapted from array-move
+function moveItem([...arr], fromIndex, toIndex) {
+    const startIndex = fromIndex < 0 ? arr.length + fromIndex : fromIndex;
+    if (startIndex >= 0 && startIndex < arr.length) {
+        const endIndex = toIndex < 0 ? arr.length + toIndex : toIndex;
+        const [item] = arr.splice(fromIndex, 1);
+        arr.splice(endIndex, 0, item);
+    }
+    return arr;
+}
+
+export { addUniqueItem, moveItem, removeItem };