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/autoprefixer/README.md

@@ -0,0 +1,56 @@
+# Autoprefixer [![Cult Of Martians][cult-img]][cult]
+
+<img align="right" width="94" height="71"
+     src="https://postcss.github.io/autoprefixer/logo.svg"
+     title="Autoprefixer logo by Anton Lovchikov">
+
+[PostCSS] plugin to parse CSS and add vendor prefixes to CSS rules using values
+from [Can I Use]. It is recommended by Google and used in Twitter and Alibaba.
+
+Write your CSS rules without vendor prefixes (in fact, forget about them
+entirely):
+
+```css
+::placeholder {
+  color: gray;
+}
+
+.image {
+  width: stretch;
+}
+```
+
+Autoprefixer will use the data based on current browser popularity and property
+support to apply prefixes for you. You can try the [interactive demo]
+of Autoprefixer.
+
+```css
+::-moz-placeholder {
+  color: gray;
+}
+::placeholder {
+  color: gray;
+}
+
+.image {
+  width: -webkit-fill-available;
+  width: -moz-available;
+  width: stretch;
+}
+```
+
+Twitter account for news and releases: [@autoprefixer].
+
+<a href="https://evilmartians.com/?utm_source=autoprefixer">
+<img src="https://evilmartians.com/badges/sponsored-by-evil-martians.svg" alt="Sponsored by Evil Martians" width="236" height="54">
+</a>
+
+[interactive demo]: https://autoprefixer.github.io/
+[@autoprefixer]: https://twitter.com/autoprefixer
+[Can I Use]: https://caniuse.com/
+[cult-img]: https://cultofmartians.com/assets/badges/badge.svg
+[PostCSS]: https://github.com/postcss/postcss
+[cult]: https://cultofmartians.com/tasks/autoprefixer-grid.html
+
+## Docs
+Read full docs **[here](https://github.com/postcss/autoprefixer#readme)**.