Lanshuns/Qwacky ? reverse-engineered prompt

Build me a privacy focused browser extension called Qwacky that works in both Chrome and Firefox and lets people use DuckDuckGo Email Protection on its own.

I want a simple extension where users can create and manage @duck.com aliases, keep them organized with notes and tags, search and filter them, and switch between multiple accounts if they have more than one. It should also help fill email fields on websites from a right click menu or a keyboard shortcut, and let users turn a recipient into a duck.com address when sending something privately.

Please keep everything stored locally, with no tracking or analytics, and make it easy to back up and restore data or sync it across devices. The app should feel lightweight and focused just on email protection, not like the full DuckDuckGo extension. Make sure the Chrome and Firefox versions both work cleanly with the right permissions for each browser. If you need to check the latest extension docs online, go ahead.