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/pure-rand/lib/esm/distribution/UnsafeUniformArrayIntDistribution.js

@@ -0,0 +1,8 @@
+import { addArrayIntToNew, addOneToPositiveArrayInt, substractArrayIntToNew, trimArrayIntInplace, } from './internals/ArrayInt.js';
+import { unsafeUniformArrayIntDistributionInternal } from './internals/UnsafeUniformArrayIntDistributionInternal.js';
+export function unsafeUniformArrayIntDistribution(from, to, rng) {
+    var rangeSize = trimArrayIntInplace(addOneToPositiveArrayInt(substractArrayIntToNew(to, from)));
+    var emptyArrayIntData = rangeSize.data.slice(0);
+    var g = unsafeUniformArrayIntDistributionInternal(emptyArrayIntData, rangeSize.data, rng);
+    return trimArrayIntInplace(addArrayIntToNew({ sign: 1, data: g }, from));
+}