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/is-number-object/index.js

@@ -0,0 +1,29 @@
+'use strict';
+
+var callBound = require('call-bound');
+
+var $numToStr = callBound('Number.prototype.toString');
+
+/** @type {import('.')} */
+var tryNumberObject = function tryNumberObject(value) {
+	try {
+		$numToStr(value);
+		return true;
+	} catch (e) {
+		return false;
+	}
+};
+var $toString = callBound('Object.prototype.toString');
+var numClass = '[object Number]';
+var hasToStringTag = require('has-tostringtag/shams')();
+
+/** @type {import('.')} */
+module.exports = function isNumberObject(value) {
+	if (typeof value === 'number') {
+		return true;
+	}
+	if (!value || typeof value !== 'object') {
+		return false;
+	}
+	return hasToStringTag ? tryNumberObject(value) : $toString(value) === numClass;
+};