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/webpack/lib/node/NodeEnvironmentPlugin.js

@@ -0,0 +1,75 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+const CachedInputFileSystem = require("enhanced-resolve").CachedInputFileSystem;
+const fs = require("graceful-fs");
+const createConsoleLogger = require("../logging/createConsoleLogger");
+const NodeWatchFileSystem = require("./NodeWatchFileSystem");
+const nodeConsole = require("./nodeConsole");
+
+/** @typedef {import("../../declarations/WebpackOptions").InfrastructureLogging} InfrastructureLogging */
+/** @typedef {import("../Compiler")} Compiler */
+/** @typedef {import("../util/fs").InputFileSystem} InputFileSystem */
+
+/**
+ * Defines the node environment plugin options type used by this module.
+ * @typedef {object} NodeEnvironmentPluginOptions
+ * @property {InfrastructureLogging} infrastructureLogging infrastructure logging options
+ */
+
+const PLUGIN_NAME = "NodeEnvironmentPlugin";
+
+class NodeEnvironmentPlugin {
+	/**
+	 * Creates an instance of NodeEnvironmentPlugin.
+	 * @param {NodeEnvironmentPluginOptions} options options
+	 */
+	constructor(options) {
+		/** @type {NodeEnvironmentPluginOptions} */
+		this.options = options;
+	}
+
+	/**
+	 * Applies the plugin by registering its hooks on the compiler.
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
+	apply(compiler) {
+		const { infrastructureLogging } = this.options;
+		compiler.infrastructureLogger = createConsoleLogger({
+			level: infrastructureLogging.level || "info",
+			debug: infrastructureLogging.debug || false,
+			console:
+				infrastructureLogging.console ||
+				nodeConsole({
+					colors: infrastructureLogging.colors,
+					appendOnly: infrastructureLogging.appendOnly,
+					stream:
+						/** @type {NodeJS.WritableStream} */
+						(infrastructureLogging.stream)
+				})
+		});
+		compiler.inputFileSystem = new CachedInputFileSystem(fs, 60000);
+		const inputFileSystem =
+			/** @type {InputFileSystem} */
+			(compiler.inputFileSystem);
+		compiler.outputFileSystem = fs;
+		compiler.intermediateFileSystem = fs;
+		compiler.watchFileSystem = new NodeWatchFileSystem(inputFileSystem);
+		compiler.hooks.beforeRun.tap(PLUGIN_NAME, (compiler) => {
+			if (
+				compiler.inputFileSystem === inputFileSystem &&
+				inputFileSystem.purge
+			) {
+				compiler.fsStartTime = Date.now();
+				inputFileSystem.purge();
+			}
+		});
+	}
+}
+
+module.exports = NodeEnvironmentPlugin;