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/projection/node/group.mjs

@@ -0,0 +1,24 @@
+const notify = (node) => !node.isLayoutDirty && node.willUpdate(false);
+function nodeGroup() {
+    const nodes = new Set();
+    const subscriptions = new WeakMap();
+    const dirtyAll = () => nodes.forEach(notify);
+    return {
+        add: (node) => {
+            nodes.add(node);
+            subscriptions.set(node, node.addEventListener("willUpdate", dirtyAll));
+        },
+        remove: (node) => {
+            nodes.delete(node);
+            const unsubscribe = subscriptions.get(node);
+            if (unsubscribe) {
+                unsubscribe();
+                subscriptions.delete(node);
+            }
+            dirtyAll();
+        },
+        dirty: dirtyAll,
+    };
+}
+
+export { nodeGroup };