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-abstract/helpers/intToBinaryString.js

@@ -0,0 +1,21 @@
+'use strict';
+
+var $floor = require('math-intrinsics/floor');
+
+// https://runestone.academy/ns/books/published/pythonds/BasicDS/ConvertingDecimalNumberstoBinaryNumbers.html#:~:text=The%20Divide%20by%202%20algorithm,have%20a%20remainder%20of%200
+
+module.exports = function intToBinaryString(x) {
+	var str = '';
+	var y;
+
+	while (x > 0) {
+		y = x / 2;
+		x = $floor(y); // eslint-disable-line no-param-reassign
+		if (y === x) {
+			str = '0' + str;
+		} else {
+			str = '1' + str;
+		}
+	}
+	return str;
+};