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/2025/IteratorStep.js

@@ -0,0 +1,35 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+
+var IteratorComplete = require('./IteratorComplete');
+var IteratorNext = require('./IteratorNext');
+
+var isIteratorRecord = require('../helpers/records/iterator-record');
+
+// https://262.ecma-international.org/16.0/#sec-iteratorstep
+
+module.exports = function IteratorStep(iteratorRecord) {
+	if (!isIteratorRecord(iteratorRecord)) {
+		throw new $TypeError('Assertion failed: `iteratorRecord` must be an Iterator Record'); // step 1
+	}
+
+	var result = IteratorNext(iteratorRecord); // step 1
+	try {
+		var done = IteratorComplete(result); // step 2
+	} catch (e) { // step 3
+		// eslint-disable-next-line no-param-reassign
+		iteratorRecord['[[Done]]'] = true; // step 3.a
+		throw e; // step 3.b
+
+	}
+
+	if (done) { // step 5
+		// eslint-disable-next-line no-param-reassign
+		iteratorRecord['[[Done]]'] = true; // step 5.a
+		return false; // step 5.b. should be `~done~` but `false` is more convenient here.
+	}
+
+	return result; // steps 6
+};
+