AI extensions - consider simplifying `azd ai agent/finetuning init` to call `azd init --minimal`

Currently, if there's no azd project detected, `azd ai agent/finetuning init` calls `azd init` interactively, which presents 3 options:
<img width="800" height="194" alt="Image" src="https://github.com/user-attachments/assets/66be6140-660f-4fd8-863e-671a0ab5e43c" />

We've gotten feedback it's not clear what users should pick here