Rubber Duck - Specify Model

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

Specify which model rubber duck mode uses

### Proposed solution

Currently there is not a method for specifying what model the rubber duck mode uses, so sometimes it's using 3x or even 7x models like opus 4.7

It would be nice to have a /rubber-duck model command or similar to select what it uses, or which models it can select from automatically

### Example prompts or workflows

_No response_

### Additional context

Rubber-duck(claude-opus-4.7) Critique ..............REDACTED.................

Start by locating the rubber-duck mode entry point and tracing how it chooses a model. Compare the requested /rubber-duck model command with automatic selection behavior, then define a testable model-selection workflow; done means the selected or allowed models are honored.

Scritto dal modello di indicizzazione a partire dal testo della issue.