What does this MR do and why?

Adds the ability to resize the AI input field to being able to put larger questions in (e.g. code blocks).

• Auto increases the height until 240px
• Adds scrolling beyond 240px
• Shift + Enter will add a new line
• Enter will submit

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Help > Ask GitLab Chat
2. Enter a long question
3. Verify input field

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.