Command Palette: Change Tab key to switch options in Results list

### Description of the new feature / enhancement

Currently, pressing Tab in the Command Palette moves focus to the first option and then to other UI elements (e.g., Settings → Search Apps). I would love Tab cycle through the results list items directly.

### Scenario when this would be used?

This would improve UX by allowing users to navigate results without moving their right hand to the arrow keys.

### Supporting information

_No response_

Start in the Command Palette implementation by tracing how keyboard focus moves into the Results list and how Tab is currently handled. Verify the existing navigation behavior, then confirm that Tab cycles through result items without moving to unrelated UI elements and test the change in the Command Palette.

Written by the indexing model from the issue text.