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/argparse/package.json

@@ -0,0 +1,34 @@
+{
+  "name": "argparse",
+  "description": "Very powerful CLI arguments parser. Native port of argparse - python's options parsing library",
+  "version": "1.0.10",
+  "keywords": [
+    "cli",
+    "parser",
+    "argparse",
+    "option",
+    "args"
+  ],
+  "contributors": [
+    "Eugene Shkuropat",
+    "Paul Jacobson"
+  ],
+  "files": [
+    "index.js",
+    "lib/"
+  ],
+  "license": "MIT",
+  "repository": "nodeca/argparse",
+  "scripts": {
+    "test": "make test"
+  },
+  "dependencies": {
+    "sprintf-js": "~1.0.2"
+  },
+  "devDependencies": {
+    "eslint": "^2.13.1",
+    "istanbul": "^0.4.5",
+    "mocha": "^3.1.0",
+    "ndoc": "^5.0.1"
+  }
+}