Feature: User input highlighting/styling in terminal

Description

It would be helpful to have the ability to customize the styling of user input in Claude Code's terminal to make it more visually distinct from Claude's responses.

Use Case

When reviewing terminal conversations, it's sometimes hard to quickly scan and identify where the user's questions are versus Claude's responses. A visual distinction would improve readability.

Suggested Implementation

Add settings to customize user input appearance, such as:

• Background color highlighting (e.g., yellowish background)
• Text color or bold styling

Any standard highlighting convention used in other terminal applications would work well.

Additional Context

Currently, Claude Code's visual appearance is determined by the terminal application's theme, with no built-in styling options for user input specifically. A feature to distinguish user messages could be added to settings.json or similar configuration.