If the user has no void env vars set, instead of displaying the chat, we should display setup instructions. We need to ask users to add their own environment variable API keys (e.g. void.anthropicKey). We also need to give users setup instructions for using Ollama, see #22.

Ideally users input their API keys inside in the sidebar's setup UI without having to go into settings. Or, we give links that bring them directly to settings and don't make them search.

For reference, see dev instructions for setting up void env vars here: https://github.com/voideditor/void/blob/main/CONTRIBUTING.md#1-building-the-extension