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/core-js-pure/full/map/group-by.js

@@ -0,0 +1,20 @@
+'use strict';
+var parent = require('../../actual/map/group-by');
+require('../../modules/esnext.map.delete-all');
+require('../../modules/esnext.map.emplace');
+require('../../modules/esnext.map.every');
+require('../../modules/esnext.map.filter');
+require('../../modules/esnext.map.find');
+require('../../modules/esnext.map.find-key');
+require('../../modules/esnext.map.get-or-insert');
+require('../../modules/esnext.map.get-or-insert-computed');
+require('../../modules/esnext.map.includes');
+require('../../modules/esnext.map.key-of');
+require('../../modules/esnext.map.map-keys');
+require('../../modules/esnext.map.map-values');
+require('../../modules/esnext.map.merge');
+require('../../modules/esnext.map.reduce');
+require('../../modules/esnext.map.some');
+require('../../modules/esnext.map.update');
+
+module.exports = parent;