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/path-parse/package.json

@@ -0,0 +1,33 @@
+{
+  "name": "path-parse",
+  "version": "1.0.7",
+  "description": "Node.js path.parse() ponyfill",
+  "main": "index.js",
+  "scripts": {
+    "test": "node test.js"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/jbgutierrez/path-parse.git"
+  },
+  "keywords": [
+    "path",
+    "paths",
+    "file",
+    "dir",
+    "parse",
+    "built-in",
+    "util",
+    "utils",
+    "core",
+    "ponyfill",
+    "polyfill",
+    "shim"
+  ],
+  "author": "Javier Blanco <http://jbgutierrez.info>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/jbgutierrez/path-parse/issues"
+  },
+  "homepage": "https://github.com/jbgutierrez/path-parse#readme"
+}