Knuspr.de support

[xuio]

I started to implement support for Knuspr.de (German version of rohlik.cz). I just built a quick and dirty implementation here: https://github.com/xuio/HA-RohlikCZ

I did not create a pull request yet, because it's just a quick and dirty implementation using cursor agent mode and I did not really test it properly yet.

It would be good to get some feedback! (Please don't mind the changes in formatting, it was done automatically by the vscode hass-devcontainer default config.)

[dvejsada]

Sure, if knuspr.de uses the same API, it should not be a problem. But please test it properly first (I do not have the possibility to test it).