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/GetMatchString.js

@@ -0,0 +1,26 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+
+var substring = require('./substring');
+
+var isMatchRecord = require('../helpers/records/match-record');
+
+// https://262.ecma-international.org/13.0/#sec-getmatchstring
+
+module.exports = function GetMatchString(S, match) {
+	if (typeof S !== 'string') {
+		throw new $TypeError('Assertion failed: `S` must be a String');
+	}
+	if (!isMatchRecord(match)) {
+		throw new $TypeError('Assertion failed: `match` must be a Match Record');
+	}
+
+	if (!(match['[[StartIndex]]'] <= S.length)) {
+		throw new $TypeError('`match` [[StartIndex]] must be a non-negative integer <= the length of S');
+	}
+	if (!(match['[[EndIndex]]'] <= S.length)) {
+		throw new $TypeError('`match` [[EndIndex]] must be an integer between [[StartIndex]] and the length of S, inclusive');
+	}
+	return substring(S, match['[[StartIndex]]'], match['[[EndIndex]]']);
+};