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/tailwindcss/lib/util/responsive.js

@@ -0,0 +1,24 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+Object.defineProperty(exports, "default", {
+    enumerable: true,
+    get: function() {
+        return responsive;
+    }
+});
+const _postcss = /*#__PURE__*/ _interop_require_default(require("postcss"));
+const _cloneNodes = /*#__PURE__*/ _interop_require_default(require("./cloneNodes"));
+function _interop_require_default(obj) {
+    return obj && obj.__esModule ? obj : {
+        default: obj
+    };
+}
+function responsive(rules) {
+    return _postcss.default.atRule({
+        name: "responsive"
+    }).append((0, _cloneNodes.default)(Array.isArray(rules) ? rules : [
+        rules
+    ]));
+}