fixerAPI/fixer — reverse-engineered prompt

Build me a simple currency exchange rates API like the old Fixer service that I can run privately on my own machine or server.

I want it to return JSON for the latest rates and also let me ask for historical rates by date, going back to 1999. By default everything should be based on EUR, but I also want to be able to pass a different base currency and optionally request only a few currencies like USD or GBP. Keep the URLs straightforward, like one endpoint for latest rates and one where the date is part of the path.

Please make it easy to start locally with Docker and have a production friendly setup using environment variables. It should pull data from the European Central Bank and update on the normal daily schedule. The main goal is a clean, reliable API that behaves like the classic fixer style service and is easy for a browser app or small frontend to consume. If anything is unclear, check the current public docs and match the old API behavior as closely as makes sense.