Power button action

## Feature Description

A setting to change what the power button does.

## Use Case

Current action is to shutdown on power button, when on a laptop generally it would be better for most people for this to be a sleep button.

## Compositor

Is this feature specific to one compositor?

- [X ] All compositors
- [ ] niri
- [ ] Hyprland
- [ ] dwl (MangoWC)
- [ ] sway

## Proposed Solution

Maybe with a drop-down menu in the power section of settings.

## Alternatives/Existing Solutions

Included in most DEs by default.

Start by locating the power section of settings and the existing power-button shutdown action. Check how the behavior applies across all listed compositors; done means a setting lets users choose the power-button action, including sleep, and the selected action works consistently.

Written by the indexing model from the issue text.