🔧 refactor: Enable Scrolling Chat Message with PageDown and PageUp keys

[ohneda]

Summary

Enabled scrolling through chat messages using the PageUp and PageDown keys by adding tabIndex={0}. This change is intended to improve accessibility.

Change Type

• [x] Refactoring

Testing

Verified that chat messages can be scrolled using the PageUp and PageDown keys.

Checklist

Please delete any irrelevant options.

• [x] My code adheres to this project's style guidelines
• [x] I have performed a self-review of my own code
• [x] My changes do not introduce new warnings
• [x] Local unit tests pass with my changes