Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
(Arguably no, but it's an okay compromise methinks)
- [ ] Tests cover the new/changed behavior (I'm unsure how one would
properly test this, sorry!)
- [x] Performance impact has been considered and is acceptable

Closes #56466

To be completely honest I don't know if this is a good fix or not, it
does fix the problem I was running into where opening the large mermaid
diagram would blow up VRAM. It doesn't look amazing visually but I would
consider this behavior better, if it's not a good fix then that's okay:)

I chose 8192 because 8192 only brings VRAM usage up ~100MB in my testing
while 16384 brought my VRAM usage up to about 1GB from 150-200MB, for
lower end systems this seems unacceptable.

Before:
I can't take a screenshot of the before at this point because it eats my
system VRAM & Memory too fast. As a text description; It would show a
large empty rectangle where the mermaid diagram should be and blow up
Zed's VRAM usage from ~300MB to ~22GB (all of the available VRAM in my
system)

After:
<img width="1698" height="763" alt="image"
src="https://github.com/user-attachments/assets/62eb7c95-cca8-43f9-8257-c7e529f26e8d"
/>
<img width="1000" height="31" alt="image"
src="https://github.com/user-attachments/assets/4315c029-3cdd-44f6-ac78-971d125ab700"
/> (Up from ~150MB), the 257MiB figure is the GPU Memory.

Release Notes:

- N/A?

Co-authored-by: Lukas Wirth <lukas@zed.dev>