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/jest-validate/build/validateCLIOptions.d.ts

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+import type { Options } from 'yargs';
+import type { Config } from '@jest/types';
+import type { DeprecatedOptions } from './types';
+export declare const DOCUMENTATION_NOTE: string;
+export default function validateCLIOptions(argv: Config.Argv, options: {
+    deprecationEntries: DeprecatedOptions;
+    [s: string]: Options;
+}, rawArgv?: Array<string>): boolean;