Allow scrolling through the current conversation history

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

● Describe the feature or problem you'd like to solve ┃ In Copilot CLI, using the mouse wheel or PageUp/PageDown navigates through prompt history instead of scrolling the ┃ current conversation. ┃ ┃ When the conversation becomes long, I cannot scroll up to review earlier messages at the top of the same ┃ conversation. This makes it difficult to refer back to previous requirements, responses, and context.

### Proposed solution

Provide a way to scroll through the current conversation independently from prompt-history navigation.
Mouse-wheel scrolling and PageUp/PageDown should scroll the conversation view, while prompt-history navigation
should use separate configurable keybindings.

### Example prompts or workflows

_No response_

### Additional context

1. Have a long conversation with multiple prompts and responses.
2. Scroll upward to review messages from earlier in the same conversation.
3. Use PageUp/PageDown to move through the conversation history.
4. Use separate keys when navigating previously entered prompts.

Comienza en el manejo de la entrada y de la conversation-view del Copilot CLI para los eventos de mouse-wheel y PageUp/PageDown. Traza cómo esas teclas navegan actualmente por el historial del prompt y, después, identifica la configuración existente de keybindings; se considera terminado cuando el desplazamiento revisa los mensajes anteriores de la conversación actual, mientras que la navegación del historial del prompt usa teclas configurables independientes.

Escrito por el modelo de indexación a partir del texto del issue.