fix(core): ai image upload failed (#13405)

Close [AI-407](https://linear.app/affine-design/issue/AI-407)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Bug Fixes**
* Ensured that images included in the chat context are now properly sent
as attachments during AI chat interactions.

* **Tests**
* Enhanced chat tests to verify that the AI correctly identifies images
of kittens or cats in its responses.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/core/src/blocksuite/ai/components/ai-chat-input/ai-chat-input.ts

@@ -700,7 +700,7 @@ export class AIChatInput extends SignalWatcher(
               : undefined,
         },
         docId: this.docId,
-        attachments: [],
+        attachments: images,
         workspaceId: this.workspaceId,
         stream: true,
         signal: abortController.signal,