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/SetFunctionLength.js

@@ -0,0 +1,28 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+var isInteger = require('math-intrinsics/isInteger');
+
+var DefinePropertyOrThrow = require('./DefinePropertyOrThrow');
+var HasOwnProperty = require('./HasOwnProperty');
+var IsExtensible = require('./IsExtensible');
+
+// https://262.ecma-international.org/12.0/#sec-setfunctionlength
+
+module.exports = function SetFunctionLength(F, length) {
+	if (typeof F !== 'function' || !IsExtensible(F) || HasOwnProperty(F, 'length')) {
+		throw new $TypeError('Assertion failed: `F` must be an extensible function and lack an own `length` property');
+	}
+	if (typeof length !== 'number') {
+		throw new $TypeError('Assertion failed: `length` must be a Number');
+	}
+	if (length !== Infinity && (!isInteger(length) || length < 0)) {
+		throw new $TypeError('Assertion failed: `length` must be ∞, or an integer >= 0');
+	}
+	return DefinePropertyOrThrow(F, 'length', {
+		'[[Configurable]]': true,
+		'[[Enumerable]]': false,
+		'[[Value]]': length,
+		'[[Writable]]': false
+	});
+};