Feat: Getting Started tasks

[acidbubbles]

As additional backends get added, it's becoming harder to understand all the pieces. I suggest to add a simple "getting started" menu that becomes hidden when complete. In short:

• It's simply a list of tasks, such as "Select and configure an AI backend", "Select and configure an image backend" etc.
• You can say "done" and it disappears
• Once they are all done, the whole thing disappears
• When something is not done, it can add insights in the relevant screens, such as "what's an AI backend" in the backends screen.

A little like vscode has when you launch it.

It's just an idea, I'm curious what you guys think. It's also a good balance between explaining lots of stuff without making the screens full of useless texts for advanced users.