lgidon/Dolphin_Boiler_Monitor ? reverse-engineered prompt

Build me a small FastAPI service that monitors my Dolphin smart boiler controller and gives me a clean API to work with it from my laptop or other apps.

It should regularly poll the Dolphin cloud service in the background, save the readings in a local SQLite database, and let me view the current status plus past telemetry over a chosen time range. I also want simple endpoints to turn the boiler on or off remotely. If the Dolphin API has a temporary problem, the poller should keep running and recover instead of crashing.

Please include a Swagger style docs page, a Docker setup, and environment based config for things like my Dolphin login, API key, device name, and polling interval. Use current docs online if you need to. I’d also like basic tests for the client, polling, database, and routes, with good coverage so it feels solid and ready to run.