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/@sinonjs/commons/lib/index.test.js

@@ -0,0 +1,31 @@
+"use strict";
+
+var assert = require("@sinonjs/referee-sinon").assert;
+var index = require("./index");
+
+var expectedMethods = [
+    "calledInOrder",
+    "className",
+    "every",
+    "functionName",
+    "orderByFirstCall",
+    "typeOf",
+    "valueToString",
+];
+var expectedObjectProperties = ["deprecated", "prototypes"];
+
+describe("package", function () {
+    // eslint-disable-next-line mocha/no-setup-in-describe
+    expectedMethods.forEach(function (name) {
+        it(`should export a method named ${name}`, function () {
+            assert.isFunction(index[name]);
+        });
+    });
+
+    // eslint-disable-next-line mocha/no-setup-in-describe
+    expectedObjectProperties.forEach(function (name) {
+        it(`should export an object property named ${name}`, function () {
+            assert.isObject(index[name]);
+        });
+    });
+});