Revert to Haiku 4 (multimodal support confirmed)
Haiku 4 DOES support vision/images. The server crash was due to
a bug in letta-cloud utils.py (now fixed in ea5b1c9a5).
Once server deployed, Haiku will work with images.
🐾 Generated with [Letta Code](https://letta.com)
Co-Authored-By: Letta <noreply@letta.com>