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/eslint/lib/unsupported-api.js

@@ -0,0 +1,30 @@
+/**
+ * @fileoverview APIs that are not officially supported by ESLint.
+ *      These APIs may change or be removed at any time. Use at your
+ *      own risk.
+ * @author Nicholas C. Zakas
+ */
+
+"use strict";
+
+//-----------------------------------------------------------------------------
+// Requirements
+//-----------------------------------------------------------------------------
+
+const { FileEnumerator } = require("./cli-engine/file-enumerator");
+const { FlatESLint, shouldUseFlatConfig } = require("./eslint/flat-eslint");
+const FlatRuleTester = require("./rule-tester/flat-rule-tester");
+const { ESLint } = require("./eslint/eslint");
+
+//-----------------------------------------------------------------------------
+// Exports
+//-----------------------------------------------------------------------------
+
+module.exports = {
+    builtinRules: require("./rules"),
+    FlatESLint,
+    shouldUseFlatConfig,
+    FlatRuleTester,
+    FileEnumerator,
+    LegacyESLint: ESLint
+};