Add configurable climate control button to Area card

[francesconazzaro]

The problem

The Area card currently supports control buttons for domains like light, switch, fan, and cover. These buttons toggle all entities of that domain in the area. However, for the climate domain, no such button exists.

Unlike lights or switches, controlling all climate devices at once is usually not desirable. For example, in an area with both an AC unit and a thermostat, the user likely wants to control just one of them — not both simultaneously.

Proposed solution

Add a climate control button to the Area card, but with a key difference:

• The button should not control all climate entities by default.
• Instead, users should be able to configure which climate entity the Area card button operates.
• This configuration should be accessible via Settings → Areas, allowing users to pick the default climate device for that area.

When tapped, the button will either open the climate more-info dialog for the selected entity or simply toggle it.

Thanks for considering this improvement!