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/istanbul-lib-source-maps/lib/transform-utils.js

@@ -0,0 +1,21 @@
+/*
+ Copyright 2015, Yahoo Inc.
+ Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
+ */
+'use strict';
+
+function getUniqueKey(pathname) {
+    return pathname.replace(/[\\/]/g, '_');
+}
+
+function getOutput(cache) {
+    return Object.values(cache).reduce(
+        (output, { file, mappedCoverage }) => ({
+            ...output,
+            [file]: mappedCoverage
+        }),
+        {}
+    );
+}
+
+module.exports = { getUniqueKey, getOutput };