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/jsx-ast-utils/.eslintrc

@@ -0,0 +1,20 @@
+{
+  "root": true,
+
+  "extends": "airbnb-base",
+
+  "parser": "@babel/eslint-parser",
+
+  "rules": {
+    "no-use-before-define": ["error", { "functions": false }],
+  },
+
+  "overrides": [
+    {
+      "files": "src/index.js",
+      "rules": {
+        "import/no-import-module-exports": 0,
+      },
+    },
+  ],
+}