Discussion: Cortex.cpp Model and model.yaml

## Overview

- Linked: #1040 
- Where and how do we store models?
- How do we structure model folders?
- How do we detect models?
- What is the format of our `model.yaml`?

## Docs

- https://cortex.so/docs/model-yaml
- https://github.com/janhq/jan/issues/2843
- https://github.com/janhq/jan/issues/3251 (poorly scoped)