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/WarnNoModeSetPlugin.js

@@ -0,0 +1,27 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+const NoModeWarning = require("./NoModeWarning");
+
+/** @typedef {import("./Compiler")} Compiler */
+
+const PLUGIN_NAME = "WarnNoModeSetPlugin";
+
+class WarnNoModeSetPlugin {
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
+	apply(compiler) {
+		compiler.hooks.thisCompilation.tap(PLUGIN_NAME, (compilation) => {
+			compilation.warnings.push(new NoModeWarning());
+		});
+	}
+}
+
+module.exports = WarnNoModeSetPlugin;