Add optional AI capabilities

I took a brief look at the branch, and the work in there looks pretty promising, but I want to just mention one thing that should be changed sooner rather than later, because it will block commit: the installer should not be changed at all. Configuring API keys for the AI providers will have to be done after installation, maybe as a link on the welcome dashboard.

The installer is extremely opinionated and meant to be over as quick as possible. Any kind of post-install configuration, including setting API keys, has to be done after the fact.

My suggestion would be to revert all changes to the installer, and then later (in a follow-up issue), add the user flow for configuring API keys post-install.

@phenaproxima - Ah, sorry, I didn't see this until now. Got it, will revert and see how we can do a simple installation process post install.