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/markdownlint/style/cirosantilli.json

@@ -0,0 +1,22 @@
+{
+  "comment": "Rules for the style guide at https://www.cirosantilli.com/markdown-style-guide/",
+
+  "default": true,
+  "MD003": {
+    "style": "atx"
+  },
+  "MD004": {
+    "style": "dash"
+  },
+  "MD007": {
+    "indent": 4
+  },
+  "MD030": {
+    "ul_multi": 3,
+    "ol_multi": 2
+  },
+  "MD033": false,
+  "MD035": {
+    "style": "---"
+  }
+}