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/@wordpress/e2e-test-utils-playwright/build/request-utils/login.js

@@ -0,0 +1,22 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.login = void 0;
+async function login(user = this.user) {
+    // Login to admin using request context.
+    let response = await this.request.post('wp-login.php', {
+        failOnStatusCode: true,
+        form: {
+            log: user.username,
+            pwd: user.password,
+        },
+    });
+    await response.dispose();
+    // Get the nonce.
+    response = await this.request.get('wp-admin/admin-ajax.php?action=rest-nonce', {
+        failOnStatusCode: true,
+    });
+    const nonce = await response.text();
+    return nonce;
+}
+exports.login = login;
+//# sourceMappingURL=login.js.map