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-resolve/build/ModuleNotFoundError.d.ts

@@ -0,0 +1,18 @@
+/**
+ * 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 { Config } from '@jest/types';
+export default class ModuleNotFoundError extends Error {
+    code: string;
+    hint?: string;
+    requireStack?: Array<Config.Path>;
+    siblingWithSimilarExtensionFound?: boolean;
+    moduleName?: string;
+    private _originalMessage?;
+    constructor(message: string, moduleName?: string);
+    buildMessage(rootDir: Config.Path): void;
+    static duckType(error: ModuleNotFoundError): ModuleNotFoundError;
+}