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/unicode-match-property-value-ecmascript/package.json

@@ -0,0 +1,39 @@
+{
+  "name": "unicode-match-property-value-ecmascript",
+  "version": "2.2.1",
+  "description": "Match a Unicode property or property alias to its canonical property name per the algorithm used for RegExp Unicode property escapes in ECMAScript.",
+  "homepage": "https://github.com/mathiasbynens/unicode-match-property-value-ecmascript",
+  "main": "index.js",
+  "engines": {
+    "node": ">=4"
+  },
+  "files": [
+    "LICENSE-MIT.txt",
+    "data/mappings.js",
+    "index.js"
+  ],
+  "keywords": [
+    "unicode",
+    "unicode property values",
+    "unicode property value aliases"
+  ],
+  "license": "MIT",
+  "author": {
+    "name": "Mathias Bynens",
+    "url": "https://mathiasbynens.be/"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/mathiasbynens/unicode-match-property-value-ecmascript.git"
+  },
+  "bugs": "https://github.com/mathiasbynens/unicode-match-property-value-ecmascript/issues",
+  "devDependencies": {
+    "ava": "*",
+    "jsesc": "^3.1.0",
+    "unicode-property-value-aliases-ecmascript": "^2.2.1"
+  },
+  "scripts": {
+    "build": "node scripts/build.js",
+    "test": "ava tests/tests.js"
+  }
+}