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/object-keys/.eslintrc

@@ -0,0 +1,17 @@
+{
+	"root": true,
+
+	"extends": "@ljharb",
+
+	"rules": {
+		"complexity": [2, 23],
+		"id-length": [2, { "min": 1, "max": 40 }],
+		"max-params": [2, 3],
+		"max-statements": [2, 23],
+		"max-statements-per-line": [2, { "max": 2 }],
+		"no-extra-parens": [1],
+		"no-invalid-this": [1],
+		"no-restricted-syntax": [2, "BreakStatement", "ContinueStatement", "LabeledStatement", "WithStatement"],
+		"operator-linebreak": [2, "after"]
+	}
+}