manumura/expense-tracker ? reverse-engineered prompt

Build me a simple expense tracker web app like the one in the Firebase codealong series.

I want users to be able to add expenses, see them listed clearly, and keep everything saved so it still works after refreshing. If there are already starter and finished example folders in this repo, use the finished version as the base and make it run cleanly with my own Firebase project settings. Please wire up the Firebase config correctly, including storage if the app needs it, and make sure the setup instructions are simple enough for me to follow.

If there are a few demo versions in the repo, focus on the main app experience first and keep the UI straightforward and easy to use. If you need to check current Firebase docs or confirm anything, feel free to look it up online.