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/http-parser-js/package.json

@@ -0,0 +1,30 @@
+{
+  "name": "http-parser-js",
+  "version": "0.5.10",
+  "description": "A pure JS HTTP parser for node.",
+  "main": "http-parser.js",
+  "types": "http-parser.d.ts",
+  "scripts": {
+    "test": "python tests/test.py && node tests/iojs/test-http-parser-durability.js",
+    "testv12": "python tests/test.py --node-args=\"--http-parser=legacy\" && node --http-parser=legacy tests/iojs/test-http-parser-durability.js"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/creationix/http-parser-js.git"
+  },
+  "files": [
+    "http-parser.js",
+    "http-parser.d.ts"
+  ],
+  "keywords": [
+    "http"
+  ],
+  "author": "Tim Caswell (https://github.com/creationix)",
+  "contributors": [
+    "Jimb Esser (https://github.com/Jimbly)",
+    "Lawrence Rowe (https://github.com/lrowe)",
+    "Jan Schär (https://github.com/jscissr)",
+    "Paul Rütter (https://github.com/paulrutter)"
+  ],
+  "license": "MIT"
+}