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/es/number/virtual/index.js

@@ -0,0 +1,7 @@
+'use strict';
+require('../../../modules/es.number.to-exponential');
+require('../../../modules/es.number.to-fixed');
+require('../../../modules/es.number.to-precision');
+var entryVirtual = require('../../../internals/entry-virtual');
+
+module.exports = entryVirtual('Number');

node_modules/core-js/es/number/virtual/to-exponential.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../../modules/es.number.to-exponential');
+var getBuiltInPrototypeMethod = require('../../../internals/get-built-in-prototype-method');
+
+module.exports = getBuiltInPrototypeMethod('Number', 'toExponential');

node_modules/core-js/es/number/virtual/to-fixed.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../../modules/es.number.to-fixed');
+var getBuiltInPrototypeMethod = require('../../../internals/get-built-in-prototype-method');
+
+module.exports = getBuiltInPrototypeMethod('Number', 'toFixed');

node_modules/core-js/es/number/virtual/to-precision.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../../modules/es.number.to-precision');
+var getBuiltInPrototypeMethod = require('../../../internals/get-built-in-prototype-method');
+
+module.exports = getBuiltInPrototypeMethod('Number', 'toPrecision');