Allow tracking of spent dollar amount in session

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

Now that Github Co-Pilot is moving to API based pricing, please provide a utility to clearly track dollars spent in a session.

### Proposed solution

_No response_

### Example prompts or workflows

_No response_

### Additional context

_No response_

The issue names no file, test, or entry point. Start by locating the session and usage-accounting paths in copilot-cli, then clarify the pricing inputs and expected dollar total; done should mean a defined utility reports spending for one session.

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