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/spdx-exceptions/package.json

@@ -0,0 +1,19 @@
+{
+  "name": "spdx-exceptions",
+  "description": "list of SPDX standard license exceptions",
+  "version": "2.5.0",
+  "author": "The Linux Foundation",
+  "contributors": [
+    "Kyle E. Mitchell <kyle@kemitchell.com> (https://kemitchell.com/)"
+  ],
+  "license": "CC-BY-3.0",
+  "repository": "kemitchell/spdx-exceptions.json",
+  "files": [
+    "index.json",
+    "deprecated.json"
+  ],
+  "scripts": {
+    "build": "node build.js",
+    "latest": "node latest.js"
+  }
+}