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/@sentry/utils/dist/envelope.d.ts

@@ -0,0 +1,22 @@
+import { Envelope } from '@sentry/types';
+/**
+ * Creates an envelope.
+ * Make sure to always explicitly provide the generic to this function
+ * so that the envelope types resolve correctly.
+ */
+export declare function createEnvelope<E extends Envelope>(headers: E[0], items?: E[1]): E;
+/**
+ * Add an item to an envelope.
+ * Make sure to always explicitly provide the generic to this function
+ * so that the envelope types resolve correctly.
+ */
+export declare function addItemToEnvelope<E extends Envelope>(envelope: E, newItem: E[1][number]): E;
+/**
+ * Get the type of the envelope. Grabs the type from the first envelope item.
+ */
+export declare function getEnvelopeType<E extends Envelope>(envelope: E): string;
+/**
+ * Serializes an envelope into a string.
+ */
+export declare function serializeEnvelope(envelope: Envelope): string;
+//# sourceMappingURL=envelope.d.ts.map