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/core/build/FailedTestsInteractiveMode.d.ts

@@ -0,0 +1,31 @@
+/**
+ * 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.
+ */
+/// <reference types="node" />
+import type { AggregatedResult, AssertionLocation } from '@jest/test-result';
+declare type RunnerUpdateFunction = (failure?: AssertionLocation) => void;
+export default class FailedTestsInteractiveMode {
+    private _pipe;
+    private _isActive;
+    private _countPaths;
+    private _skippedNum;
+    private _testAssertions;
+    private _updateTestRunnerConfig?;
+    constructor(_pipe: NodeJS.WritableStream);
+    isActive(): boolean;
+    put(key: string): void;
+    run(failedTestAssertions: Array<AssertionLocation>, updateConfig: RunnerUpdateFunction): void;
+    updateWithResults(results: AggregatedResult): void;
+    private _clearTestSummary;
+    private _drawUIDone;
+    private _drawUIDoneWithSkipped;
+    private _drawUIProgress;
+    private _drawUIOverlay;
+    private _run;
+    private abort;
+    private restart;
+}
+export {};