Quickly switch between pre-set model configs

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

Enable rapid model/effort switching for better efficiency

### Proposed solution

As developer I want in many cases to use the strongest model with highest effort level available. However, typing /model, choosing the model with arrows, then choosing the effort level with right left is cumbersome and might cause be to avoid it and therefore not use the right model for the task.

My proposal is to enable mapping keyboard shortcuts to pre-set models and effort so I can quickly switch between them based on the task.
I assume there are other use cases for custom keyboard mapping.

Alternatively, add option to create custom commands, like for example "/cheap" will switch to a pre-set model I choose with pre-set effort level.
Using an approach like "/agent cheap" can work but it changes tools/behavior and not generic enough.

Another option is to create another command (e.g. "/pmodel") which shows a list of 5 pre-set model configurations I can quickly choose by number.

### Example prompts or workflows

_No response_

### Additional context

_No response_

Nell’issue non sono indicati file, test o punti di ingresso. Inizia individuando il flusso /model esistente e qualsiasi gestione delle scorciatoie da tastiera o dei comandi personalizzati. Confronta gli approcci proposti con il comportamento attuale della CLI; done dovrebbe fornire un modo rapido per passare da una configurazione preimpostata di modello e impegno a un’altra.

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