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/util/Semaphore.js

@@ -0,0 +1,51 @@
+/*
+	MIT License http://www.opensource.org/licenses/mit-license.php
+	Author Tobias Koppers @sokra
+*/
+
+"use strict";
+
+class Semaphore {
+	/**
+	 * Creates an instance of Semaphore.
+	 * @param {number} available the amount available number of "tasks"
+	 * in the Semaphore
+	 */
+	constructor(available) {
+		this.available = available;
+		/** @type {(() => void)[]} */
+		this.waiters = [];
+		/** @private */
+		this._continue = this._continue.bind(this);
+	}
+
+	/**
+	 * @param {() => void} callback function block to capture and run
+	 * @returns {void}
+	 */
+	acquire(callback) {
+		if (this.available > 0) {
+			this.available--;
+			callback();
+		} else {
+			this.waiters.push(callback);
+		}
+	}
+
+	release() {
+		this.available++;
+		if (this.waiters.length > 0) {
+			process.nextTick(this._continue);
+		}
+	}
+
+	_continue() {
+		if (this.available > 0 && this.waiters.length > 0) {
+			this.available--;
+			const callback = /** @type {(() => void)} */ (this.waiters.pop());
+			callback();
+		}
+	}
+}
+
+module.exports = Semaphore;