Feature Request: Ability to configure multiple providers and toggle between them #629

When we first run this tool, it prompts us to choose a specific provider. After that, there isn't an easy way to add new providers.
Ideally, we could retrigger that provider configuration window and have multiple providers configured.
Then, when we run /models it could display all models from all providers (maybe with the provider name prefixed before the model name so that it's easy to fuzzy search)