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/serialization/SingleItemMiddleware.js

@@ -0,0 +1,36 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+*/
+
+"use strict";
+
+const SerializerMiddleware = require("./SerializerMiddleware");
+
+/** @typedef {EXPECTED_ANY} DeserializedType */
+/** @typedef {EXPECTED_ANY[]} SerializedType */
+/** @typedef {{}} Context */
+
+/**
+ * @extends {SerializerMiddleware<DeserializedType, SerializedType, Context>}
+ */
+class SingleItemMiddleware extends SerializerMiddleware {
+	/**
+	 * @param {DeserializedType} data data
+	 * @param {Context} context context object
+	 * @returns {SerializedType | Promise<SerializedType> | null} serialized data
+	 */
+	serialize(data, context) {
+		return [data];
+	}
+
+	/**
+	 * @param {SerializedType} data data
+	 * @param {Context} context context object
+	 * @returns {DeserializedType | Promise<DeserializedType>} deserialized data
+	 */
+	deserialize(data, context) {
+		return data[0];
+	}
+}
+
+module.exports = SingleItemMiddleware;