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/nanoid/non-secure/index.js

@@ -0,0 +1,21 @@
+let urlAlphabet =
+  'useandom-26T198340PX75pxJACKVERYMINDBUSHWOLF_GQZbfghjklqvwyzrict'
+let customAlphabet = (alphabet, defaultSize = 21) => {
+  return (size = defaultSize) => {
+    let id = ''
+    let i = size | 0
+    while (i--) {
+      id += alphabet[(Math.random() * alphabet.length) | 0]
+    }
+    return id
+  }
+}
+let nanoid = (size = 21) => {
+  let id = ''
+  let i = size | 0
+  while (i--) {
+    id += urlAlphabet[(Math.random() * 64) | 0]
+  }
+  return id
+}
+export { nanoid, customAlphabet }