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/find-file-up/LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2015-2016, Jon Schlinkert.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

node_modules/find-file-up/README.md

@@ -0,0 +1,86 @@
+# find-file-up [![NPM version](https://img.shields.io/npm/v/find-file-up.svg?style=flat)](https://www.npmjs.com/package/find-file-up) [![NPM downloads](https://img.shields.io/npm/dm/find-file-up.svg?style=flat)](https://npmjs.org/package/find-file-up) [![Build Status](https://img.shields.io/travis/jonschlinkert/find-file-up.svg?style=flat)](https://travis-ci.org/jonschlinkert/find-file-up)
+
+Find a file, starting with the given cwd and recursively searching up one directory until it's found (or we run out of directories). Async and sync.
+
+## Install
+
+Install with [npm](https://www.npmjs.com/):
+
+```sh
+$ npm install --save find-file-up
+```
+
+## Usage
+
+```js
+var findFile = require('find-file-up');
+```
+
+**async**
+
+```js
+// find `foo.txt` starting at the given directory
+findFile('foo.txt', '.', function(err, fp) {
+  //=> /Users/jonschlinkert/dev/find-file-up/fixtures/foo.txt
+});
+
+// search user home
+findFile('foo.txt', '~/', function(err, fp) {
+  //=> /Users/jonschlinkert/foo.txt
+});
+```
+
+**sync**
+
+```js
+var file = findFile.sync('foo.txt', 'a/b/c/');
+```
+
+## About
+
+### Related projects
+
+* [find-pkg](https://www.npmjs.com/package/find-pkg): Find the first directory with a package.json, recursing up, starting with the given directory. Similar… [more](https://github.com/jonschlinkert/find-pkg) | [homepage](https://github.com/jonschlinkert/find-pkg "Find the first directory with a package.json, recursing up, starting with the given directory. Similar to look-up but does not support globs and only searches for package.json. Async and sync.")
+* [findup-sync](https://www.npmjs.com/package/findup-sync): Find the first file matching a given pattern in the current directory or the nearest… [more](https://github.com/cowboy/node-findup-sync) | [homepage](https://github.com/cowboy/node-findup-sync "Find the first file matching a given pattern in the current directory or the nearest ancestor directory.")
+* [global-modules](https://www.npmjs.com/package/global-modules): The directory used by npm for globally installed npm modules. | [homepage](https://github.com/jonschlinkert/global-modules "The directory used by npm for globally installed npm modules.")
+* [global-prefix](https://www.npmjs.com/package/global-prefix): Get the npm global path prefix. | [homepage](https://github.com/jonschlinkert/global-prefix "Get the npm global path prefix.")
+* [load-module-pkg](https://www.npmjs.com/package/load-module-pkg): Load the package.json for any project currently installed in node_modules. | [homepage](https://github.com/jonschlinkert/load-module-pkg "Load the package.json for any project currently installed in node_modules.")
+* [load-pkg](https://www.npmjs.com/package/load-pkg): Loads the package.json from the root of the user's current project. | [homepage](https://github.com/jonschlinkert/load-pkg "Loads the package.json from the root of the user's current project.")
+
+### Contributing
+
+Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
+
+### Building docs
+
+_(This document was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme) (a [verb](https://github.com/verbose/verb) generator), please don't edit the readme directly. Any changes to the readme must be made in [.verb.md](.verb.md).)_
+
+To generate the readme and API documentation with [verb](https://github.com/verbose/verb):
+
+```sh
+$ npm install -g verb verb-generate-readme && verb
+```
+
+### Running tests
+
+Install dev dependencies:
+
+```sh
+$ npm install -d && npm test
+```
+
+### Author
+
+**Jon Schlinkert**
+
+* [github/jonschlinkert](https://github.com/jonschlinkert)
+* [twitter/jonschlinkert](http://twitter.com/jonschlinkert)
+
+### License
+
+Copyright © 2016, [Jon Schlinkert](https://github.com/jonschlinkert).
+Released under the [MIT license](https://github.com/jonschlinkert/find-file-up/blob/master/LICENSE).
+
+***
+
+_This file was generated by [verb](https://github.com/verbose/verb), v0.9.0, on July 18, 2016._

node_modules/find-file-up/index.js

@@ -0,0 +1,102 @@
+/*!
+ * find-pkg <https://github.com/jonschlinkert/find-pkg>
+ *
+ * Copyright (c) 2015, Jon Schlinkert.
+ * Licensed under the MIT License.
+ */
+
+'use strict';
+
+/**
+ * Module dependencies
+ */
+
+var fs = require('fs');
+var path = require('path');
+var resolve = require('resolve-dir');
+var existsSync = require('fs-exists-sync');
+
+/**
+ * Find a file, starting with the given directory
+ */
+
+module.exports = function(filename, cwd, limit, cb) {
+  if (typeof cwd === 'function') {
+    cb = cwd;
+    cwd = null;
+  }
+
+  if (typeof limit === 'function') {
+    cb = limit;
+    limit = Infinity;
+  }
+
+  var dir = cwd ? resolve(cwd) : '.';
+  var n = 0;
+  var drive = path.resolve(path.sep);
+
+  (function find(dir, next) {
+    var fp = path.resolve(dir, filename);
+
+    exists(fp, function(exists) {
+      n++;
+
+      if (exists) {
+        next(null, fp);
+        return;
+      }
+
+      if (n >= limit || dir === path.sep || dir === '.' || dir === drive) {
+        next();
+        return;
+      }
+
+      find(path.dirname(dir), next);
+    });
+  }(dir, cb));
+};
+
+module.exports.sync = function(filename, cwd, limit) {
+  var dir = cwd ? resolve(cwd) : '.';
+  var fp = path.join(dir, filename);
+  var n = 0;
+  var drive = path.resolve(path.sep);
+
+  if (existsSync(fp)) {
+    return path.resolve(fp);
+  }
+
+  if (limit === 0) return null;
+
+  while ((dir = path.dirname(dir))) {
+    n++;
+
+    var filepath = path.resolve(dir, filename);
+    if (existsSync(filepath)) {
+      return filepath;
+    }
+
+    if (n >= limit || dir === '.' || dir === path.sep || dir === drive) {
+      return;
+    }
+  }
+};
+
+/**
+ * Returns true if a file exists. `fs.exists` and `fs.existsSync` are deprecated.
+ * See: https://nodejs.org/api/fs.html#fs_fs_exists_path_callback
+ */
+
+function exists(filepath, cb) {
+  (fs.access || fs.stat)(filepath, function(err) {
+    if (err && err.code === 'ENOENT') {
+      cb(false);
+      return;
+    }
+    if (err) {
+      cb(err);
+      return;
+    }
+    cb(true);
+  });
+}

node_modules/find-file-up/package.json

@@ -0,0 +1,64 @@
+{
+  "name": "find-file-up",
+  "description": "Find a file, starting with the given cwd and recursively searching up one directory until it's found (or we run out of directories). Async and sync.",
+  "version": "0.1.3",
+  "homepage": "https://github.com/jonschlinkert/find-file-up",
+  "author": "Jon Schlinkert (https://github.com/jonschlinkert)",
+  "repository": "jonschlinkert/find-file-up",
+  "bugs": {
+    "url": "https://github.com/jonschlinkert/find-file-up/issues"
+  },
+  "license": "MIT",
+  "files": [
+    "index.js",
+    "LICENSE",
+    "README.md"
+  ],
+  "main": "index.js",
+  "engines": {
+    "node": ">=0.10.0"
+  },
+  "scripts": {
+    "test": "mocha"
+  },
+  "dependencies": {
+    "fs-exists-sync": "^0.1.0",
+    "resolve-dir": "^0.1.0"
+  },
+  "devDependencies": {
+    "delete": "^0.3.2",
+    "gulp-format-md": "^0.1.9",
+    "mocha": "^2.5.3"
+  },
+  "keywords": [
+    "file",
+    "find",
+    "up"
+  ],
+  "verb": {
+    "toc": false,
+    "layout": "default",
+    "tasks": [
+      "readme"
+    ],
+    "plugins": [
+      "gulp-format-md"
+    ],
+    "related": {
+      "list": [
+        "find-pkg",
+        "findup-sync",
+        "global-modules",
+        "global-prefix",
+        "load-module-pkg",
+        "load-pkg"
+      ]
+    },
+    "reflinks": [
+      "verb"
+    ],
+    "lint": {
+      "reflinks": true
+    }
+  }
+}