Codex Micro: add chat scrolling as a knob mode

What variant of Codex are you using?

Codex desktop app with Codex Micro on macOS. App version: 26.715.72359.

What feature would you like to see?

Add a third Chat scrolling option under Settings > Codex Micro > Knob, alongside the current Reasoning only and Composer navigation modes.

When this mode is selected:

• Turning the knob clockwise scrolls down within the active chat transcript.
• Turning the knob counterclockwise scrolls up within the active chat transcript.
• The behavior remains scoped to the active Codex chat rather than scrolling another application or a system-level target.
• It works while the composer is focused and while a response is streaming.

This would make the knob useful for navigating long agent runs, command output, and review discussions without reaching for a mouse or trackpad.

Additional information

A small, consistent scroll increment per encoder detent would provide predictable navigation. This request does not require changing the existing reasoning or composer-navigation modes.