Add Desktop Environments and Window Managers section to Cachy Hello

"Hello CachyOS Team, I love the current 'CachyOS Hello' application! It would be incredibly helpful if you could add a section or button directly into CachyOS Hello that lets users easily install additional Desktop Environments and Window Managers. Currently, the Welcome app handles apps and tweaks perfectly, and having direct access to switch or install new WMs would make customizing the system even better. Thank you for all your hard work on the project!"

Start by reading the existing Cachy Hello and Welcome app/tweaks entry points to understand how application actions are exposed. Define the supported Desktop Environments and Window Managers and the intended install or switching flow; done means the new section or button provides a clear, working way to access those actions.

Written by the indexing model from the issue text.