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/@testing-library/jest-dom/dist/to-have-accessible-description.js

@@ -0,0 +1,28 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.toHaveAccessibleDescription = toHaveAccessibleDescription;
+var _domAccessibilityApi = require("dom-accessibility-api");
+var _utils = require("./utils");
+function toHaveAccessibleDescription(htmlElement, expectedAccessibleDescription) {
+  (0, _utils.checkHtmlElement)(htmlElement, toHaveAccessibleDescription, this);
+  const actualAccessibleDescription = (0, _domAccessibilityApi.computeAccessibleDescription)(htmlElement);
+  const missingExpectedValue = arguments.length === 1;
+  let pass = false;
+  if (missingExpectedValue) {
+    // When called without an expected value we only want to validate that the element has an
+    // accessible description, whatever it may be.
+    pass = actualAccessibleDescription !== '';
+  } else {
+    pass = expectedAccessibleDescription instanceof RegExp ? expectedAccessibleDescription.test(actualAccessibleDescription) : this.equals(actualAccessibleDescription, expectedAccessibleDescription);
+  }
+  return {
+    pass,
+    message: () => {
+      const to = this.isNot ? 'not to' : 'to';
+      return (0, _utils.getMessage)(this, this.utils.matcherHint(`${this.isNot ? '.not' : ''}.${toHaveAccessibleDescription.name}`, 'element', ''), `Expected element ${to} have accessible description`, expectedAccessibleDescription, 'Received', actualAccessibleDescription);
+    }
+  };
+}