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/private-apis/CHANGELOG.md

@@ -0,0 +1,69 @@
+<!-- Learn how to maintain this file at https://github.com/WordPress/gutenberg/tree/HEAD/packages#maintaining-changelogs. -->
+
+## Unreleased
+
+## 0.32.0 (2024-01-24)
+
+## 0.31.0 (2024-01-10)
+
+## 0.30.0 (2023-12-13)
+
+## 0.29.0 (2023-11-29)
+
+## 0.28.0 (2023-11-16)
+
+## 0.27.0 (2023-11-02)
+
+## 0.26.0 (2023-10-18)
+
+## 0.25.0 (2023-10-05)
+
+## 0.24.0 (2023-09-20)
+
+## 0.23.0 (2023-08-31)
+
+## 0.22.0 (2023-08-16)
+
+## 0.21.0 (2023-08-10)
+
+## 0.20.0 (2023-07-20)
+
+## 0.19.0 (2023-07-05)
+
+## 0.18.0 (2023-06-23)
+
+## 0.17.0 (2023-06-07)
+
+## 0.16.0 (2023-05-24)
+
+## 0.15.0 (2023-05-10)
+
+## 0.14.0 (2023-04-26)
+
+## 0.13.0 (2023-04-12)
+
+## 0.12.0 (2023-03-29)
+
+## 0.11.0 (2023-03-15)
+
+## 0.10.0 (2023-03-01)
+
+## 0.9.0 (2023-02-15)
+
+## 0.8.0 (2023-02-01)
+
+## 0.7.0 (2023-01-11)
+
+## 0.6.0 (2023-01-02)
+
+## 0.5.0 (2022-12-14)
+
+## 0.4.0 (2022-11-16)
+
+## 0.3.0 (2022-11-02)
+
+## 0.2.0 (2022-10-19)
+
+## 0.1.0 (2022-10-05)
+
+– Package created.