close #1994 








<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Show the model used for each assistant message in chat and persist it in
the database for transparency. Addresses #1994.

- **New Features**
  - Add model field to messages schema and Message type.
  - Set the model on assistant messages when streaming.
- Display the model with a Bot icon next to approval status in
ChatMessage.

<sup>Written for commit 181b7f919a9c29c0627b3dc74f49cf5989b7243d.
Summary will update automatically on new commits.</sup>

<!-- End of auto-generated description by cubic. -->









<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Adds transparent model tracking for assistant messages.
> 
> - Schema: add `model` to `messages` (migration + Drizzle schema) and
`Message` type
> - Streaming: set `model` on placeholder assistant messages in
`chat_stream_handlers.ts`
> - UI: show `message.model` with a Bot icon next to approval status in
`ChatMessage`
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
6411d57704648f3d92263b72681cd3fa08583152. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->