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/fork-ts-checker-webpack-plugin/lib/logger/PartialLogger.d.ts

@@ -0,0 +1,4 @@
+import Logger from './Logger';
+declare type LoggerMethods = 'info' | 'log' | 'error';
+declare function createPartialLogger(methods: LoggerMethods[], logger: Logger): Logger;
+export { createPartialLogger };