Close [AI-244](https://linear.app/affine-design/issue/AI-244)
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## Summary by CodeRabbit
* **New Features**
* Added AI chat draft persistence, allowing your chat input, quotes,
markdown, and images to be automatically saved and restored across
sessions.
* Drafts are now synchronized across chat components, so you won’t lose
your progress if you navigate away or refresh the page.
* **Improvements**
* Enhanced chat experience with seamless restoration of previously
entered content and attachments.
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