Auto selection (10% discount)

### Describe the feature or problem you'd like to solve

Using /model makes me always choose a specific model and effort when applied

### Proposed solution

When using GitHub Copilot through visual code, there is an option of "Auto (10% discount)", I do not need to necessarily specify the model that I wanna use. I would like to request the same feature for Copilot CLI please. Thank you

### Example prompts or workflows

After typing /model command:

```
Search models...

❯ Auto (10% discount)
Claude Sonnet 4.6 (default) 1x
Claude Sonnet 4.5 1x
Claude Haiku 4.5 0.33x
Claude Opus 4.6 3x
Claude Opus 4.6 (fast mode) (Preview) (requires enablement) 30x
Claude Opus 4.5 3x
Claude Sonnet 4 1x
Gemini 3 Pro (Preview) 1x
GPT-5.3-Codex 1x
GPT-5.2-Codex 1x
GPT-5.2 1x
GPT-5.1-Codex-Max 1x
GPT-5.1-Codex 1x
GPT-5.1 1x
GPT-5.1-Codex-Mini (Preview) 0.33x
GPT-5 mini 0x
GPT-4.1 ✓ 0x
```

It would have a new option on the top indicating the "Auto (10% discount)"

After selecting, I will be able to see this:

```
Auto (10% discount)
──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
❯ Type @ to mention files, / for commands, or ? for shortcuts
──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
```

### Additional context

_No response_