Chat UI overlaps the in-world theatre screen

### Build version
Not specified

### Issue Description
The chat UI panel overlaps the in-world theatre/streaming screen (the Cast/LiveKit video screen feature, e.g. the Theatre at Genesis Plaza), partially obscuring the video content behind it.

### STR (Steps to Reproduce)
1. Enter a scene with an in-world video/streaming screen (e.g. the Theatre at Genesis Plaza (0,5))
2. Have the chat UI open/visible
3. Position the camera so the theatre screen is in view

### Expected Result
The chat UI should not obscure the in-world theatre screen content.

### Actual Result with evidence
The chat UI panel overlaps part of the theatre screen, reducing visibility of the streamed content. Screenshot provided by the reporter in the originating Slack thread (not reproduced here — see Slack for the image).

### Reproduction
Unknown

### Operative system and additional Notes
Reported as a minor/cosmetic issue via Slack. No OS specified.

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Reported by Nikita Khalov
Requested by Nikita Khalov via Slack