feat: add Yolo-Auto provider

[harryvgiunta]

Adds a Yolo-Auto preset to the built-in gateway list (src/providers/presets.ts), the docs provider table, and the preset count references.

What: Yolo-Auto (https://yolo-auto.com) is an OpenAI-compatible endpoint (base https://yolo-auto.com/v1, id yolo-auto). Users paste a key in the wizard or via minicode config add, then pick the stable yolo or yolo-small alias. The full catalog is auto-discovered from GET /models, so fallbackModels stays at those two aliases.

Docs: https://yolo-auto.com/docs. Keys are free to create, no card needed.