wmandai/geofire ? reverse-engineered prompt

Build me a small JavaScript library that lets me store places by latitude and longitude in Firebase and then query for everything inside a circle on a map.

I want it to feel realtime, so if a location changes, moves in or out of the search area, or gets removed, the query updates right away. It should support adding a location, reading one back, deleting one, and creating a live query with a center and radius. Please include simple examples I can run in a browser, plus tests so I can verify the main behavior.

Use Firebase for the data, and keep the code lightweight so it can work with big datasets without loading everything at once. If you need to check anything current in the Firebase docs, look it up online.