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/builtin-modules/static.d.ts

@@ -0,0 +1,14 @@
+/**
+Static list of the Node.js builtin modules.
+
+@example
+```
+import builtinModulesStatic = require('builtin-modules/static');
+
+console.log(builtinModulesStatic);
+//=> ['assert', 'buffer', …]
+```
+*/
+declare const builtinModulesStatic: readonly string[];
+
+export = builtinModulesStatic;