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/@istanbuljs/load-nyc-config/load-esm.js

@@ -0,0 +1,12 @@
+'use strict';
+
+const {pathToFileURL} = require('url');
+
+module.exports = async filename => {
+	const mod = await import(pathToFileURL(filename));
+	if ('default' in mod === false) {
+		throw new Error(`${filename} has no default export`);
+	}
+
+	return mod.default;
+};