[FEATURE] Enhance contrast between highlighted and non-highlighted slash commands

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

If you have a few slashes starting with a prefix it's very hard to see which one you're highlighting because the text contrast between purple and black is quite marginal:

<img width="1198" height="458" alt="Image" src="https://github.com/user-attachments/assets/9f043479-fb5e-46df-9b12-5cc58d714ff7" />

<img width="1198" height="458" alt="Image" src="https://github.com/user-attachments/assets/58ca95c5-3eb1-48b7-8864-b0d6d3eca07e" />

Mockup (Via Nano Banana)

Accurate-ish:

<img width="1632" height="640" alt="Image" src="https://github.com/user-attachments/assets/f05beab0-44b6-4a57-9f09-f99436544afe" />

Proposed Solution

Some UI ideas to make it easier to see which slash you're highlighting:

Highlighted slash:

• Gets bold font
• Gets a light background shading
• Is underlined
• All of the above

Alternative Solutions

_No response_

Priority

High - Significant impact on productivity

Feature Category

Other

Use Case Example

_No response_

Additional Context

_No response_