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/es-get-iterator/node.js

@@ -0,0 +1,12 @@
+'use strict';
+
+// this should only run in node >= 13.2, so it
+// does not need any of the intense fallbacks that old node/browsers do
+
+var $iterator = Symbol.iterator;
+module.exports = function getIterator(iterable) {
+	// alternatively, `iterable[$iterator]?.()`
+	if (iterable != null && typeof iterable[$iterator] !== 'undefined') {
+		return iterable[$iterator]();
+	}
+};