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/eslint-plugin-jsx-a11y/lib/util/hasAccessibleChild.js

@@ -0,0 +1,30 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports["default"] = hasAccessibleChild;
+var _jsxAstUtils = require("jsx-ast-utils");
+var _isHiddenFromScreenReader = _interopRequireDefault(require("./isHiddenFromScreenReader"));
+function _interopRequireDefault(e) { return e && e.__esModule ? e : { "default": e }; }
+function hasAccessibleChild(node, elementType) {
+  return node.children.some(function (child) {
+    switch (child.type) {
+      case 'Literal':
+        return !!child.value;
+      // $FlowFixMe JSXText is missing in ast-types-flow
+      case 'JSXText':
+        return !!child.value;
+      case 'JSXElement':
+        return !(0, _isHiddenFromScreenReader["default"])(elementType(child.openingElement), child.openingElement.attributes);
+      case 'JSXExpressionContainer':
+        if (child.expression.type === 'Identifier') {
+          return child.expression.name !== 'undefined';
+        }
+        return true;
+      default:
+        return false;
+    }
+  }) || (0, _jsxAstUtils.hasAnyProp)(node.openingElement.attributes, ['dangerouslySetInnerHTML', 'children']);
+}
+module.exports = exports.default;