## Summary

LM Studio reports Splash models with `"compatibility_type": "splash"`.
`CompatibilityType` rejects the value, `/api/v0/models` fails to parse,
and Zed lists no LM Studio models at all. This adds a `Splash` variant.

## Testing

Tested on macOS 27 with LM Studio 0.4.45, a Splash model and an MLX
model installed. **Before**: no models. **After**: both models listed.

## Self-review

- [x] I've reviewed my diff for quality, security, reliability, and
performance.
- [ ] UI changes follow the
[checklist](https://zed.dev/docs/development/ui-checklist).
- [ ] Tests cover the new or changed behavior.

Release Notes:

- Fixed LM Studio models not appearing when a Splash model is installed.