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.

Commencez par la gestion de l’entrée et de la conversation-view dans Copilot CLI pour les événements mouse-wheel et PageUp/PageDown. Suivez la manière dont ces touches parcourent actuellement l’historique du prompt, puis identifiez la configuration existante des raccourcis clavier ; le travail est terminé lorsque le défilement permet de revoir les messages précédents de la conversation en cours, tandis que la navigation dans l’historique du prompt utilise des touches configurables distinctes.