MAJOR CHANGE (integration→helper) - PLEASE READ!
It has always been the case, that this component was not an integration - it does not talk to any device or cloud service. Instead, it computes its state internally. And this is what helpers do. But I still made it as integration, as there was not really a way to have a custom helper. This has now changed, Home Assistant went a long way towards improved usability. Not only we can now have custom helpers, but they can also be configured from GUI, and it has all the features as before. So I am moving that where it belongs.
So, from now on, you will find it under Helpers. You can create new helpers from there, or you can also create them in the integrations - but they will end up as a helper anyway.
If you'd like to change the configuration options, you find it here:
In the Related tab, you'll find other info, including the device where you can get the DIAGNOSTICS info.
Code improvements
Related to the above - they greatly improved the config flow experience, including a new set of selectors. So I took this opportunity and completely re-factored the configuration. Including moving up the configuration options where they belong - removing an old workaround that was irritating me. The configuration should be migrated automatically, so no work to be done (hopefully).