Initial commit: Developer Tools MVP with visual editor

- Complete React app with 7 developer tools
- JSON Tool with visual structured editor
- Serialize Tool with visual structured editor
- URL, Base64, CSV/JSON, Beautifier, Diff tools
- Responsive navigation with dropdown menu
- Dark/light mode toggle
- Mobile-responsive design with sticky header
- All tools working with copy/paste functionality

node_modules/webpack/lib/dependencies/SystemRuntimeModule.js

@@ -0,0 +1,35 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Florent Cailhol @ooflorent
+*/
+
+"use strict";
+
+const RuntimeGlobals = require("../RuntimeGlobals");
+const RuntimeModule = require("../RuntimeModule");
+const Template = require("../Template");
+
+class SystemRuntimeModule extends RuntimeModule {
+	constructor() {
+		super("system");
+	}
+
+	/**
+	 * @returns {string | null} runtime code
+	 */
+	generate() {
+		return Template.asString([
+			`${RuntimeGlobals.system} = {`,
+			Template.indent([
+				"import: function () {",
+				Template.indent(
+					"throw new Error('System.import cannot be used indirectly');"
+				),
+				"}"
+			]),
+			"};"
+		]);
+	}
+}
+
+module.exports = SystemRuntimeModule;