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/domexception/package.json

@@ -0,0 +1,42 @@
+{
+  "name": "domexception",
+  "description": "An implementation of the DOMException class from browsers",
+  "keywords": [
+    "dom",
+    "webidl",
+    "web idl",
+    "domexception",
+    "error",
+    "exception"
+  ],
+  "version": "4.0.0",
+  "author": "Domenic Denicola <d@domenic.me> (https://domenic.me/)",
+  "license": "MIT",
+  "repository": "jsdom/domexception",
+  "main": "index.js",
+  "files": [
+    "index.js",
+    "webidl2js-wrapper.js",
+    "lib/"
+  ],
+  "scripts": {
+    "prepare": "node scripts/generate.js",
+    "init-wpt": "node scripts/get-latest-platform-tests.js",
+    "pretest": "npm run prepare && npm run init-wpt",
+    "test": "mocha",
+    "lint": "eslint ."
+  },
+  "dependencies": {
+    "webidl-conversions": "^7.0.0"
+  },
+  "devDependencies": {
+    "@domenic/eslint-config": "^1.4.0",
+    "eslint": "^7.32.0",
+    "minipass-fetch": "^1.4.1",
+    "mocha": "^9.1.2",
+    "webidl2js": "^17.0.0"
+  },
+  "engines": {
+    "node": ">=12"
+  }
+}