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/modules/esnext.uint8-array.from-base64.js

@@ -0,0 +1,24 @@
+'use strict';
+var $ = require('../internals/export');
+var globalThis = require('../internals/global-this');
+var arrayFromConstructorAndList = require('../internals/array-from-constructor-and-list');
+var $fromBase64 = require('../internals/uint8-from-base64');
+
+var Uint8Array = globalThis.Uint8Array;
+
+var INCORRECT_BEHAVIOR_OR_DOESNT_EXISTS = !Uint8Array || !Uint8Array.fromBase64 || !function () {
+  try {
+    Uint8Array.fromBase64('', null);
+  } catch (error) {
+    return true;
+  }
+}();
+
+// `Uint8Array.fromBase64` method
+// https://github.com/tc39/proposal-arraybuffer-base64
+if (Uint8Array) $({ target: 'Uint8Array', stat: true, forced: INCORRECT_BEHAVIOR_OR_DOESNT_EXISTS }, {
+  fromBase64: function fromBase64(string /* , options */) {
+    var result = $fromBase64(string, arguments.length > 1 ? arguments[1] : undefined, null, 0x1FFFFFFFFFFFFF);
+    return arrayFromConstructorAndList(Uint8Array, result.bytes);
+  }
+});