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 <[e-mail]>

src/utils/coAgent.ts

···
       description: 'Co - A comprehensive knowledge management assistant designed to learn, adapt, and think alongside the user',
       // agentType: Letta.AgentType.LettaV1Agent, // currently pending sleeptime fixes
       // agentType: Letta.AgentType.MemgptV2Agent,
-      model: 'anthropic/claude-sonnet-4-5-20250929',
+      model: 'anthropic/claude-haiku-4-5-20251001',
       system: CO_SYSTEM_PROMPT,
       tags: [CO_TAG],
       memoryBlocks: getDefaultMemoryBlocks(),