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/parent-module/index.js

@@ -0,0 +1,37 @@
+'use strict';
+const callsites = require('callsites');
+
+module.exports = filepath => {
+	const stacks = callsites();
+
+	if (!filepath) {
+		return stacks[2].getFileName();
+	}
+
+	let seenVal = false;
+
+	// Skip the first stack as it's this function
+	stacks.shift();
+
+	for (const stack of stacks) {
+		const parentFilepath = stack.getFileName();
+
+		if (typeof parentFilepath !== 'string') {
+			continue;
+		}
+
+		if (parentFilepath === filepath) {
+			seenVal = true;
+			continue;
+		}
+
+		// Skip native modules
+		if (parentFilepath === 'module.js') {
+			continue;
+		}
+
+		if (seenVal && parentFilepath !== filepath) {
+			return parentFilepath;
+		}
+	}
+};