Close [AI-241](https://linear.app/affine-design/issue/AI-241)
Close [AI-237](https://linear.app/affine-design/issue/AI-237)
Close [AI-238](https://linear.app/affine-design/issue/AI-238)
<img width="564" alt="截屏2025-07-03 15 54 10"
src="https://github.com/user-attachments/assets/8654db2b-cb71-4906-9e3b-0a723d7459e1"
/>
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Introduced a chat toolbar with options to create new sessions and
pin/unpin chat sessions.
* Enhanced session management, allowing users to pin sessions and
control session reuse.
* Added the ability to update session properties directly from the chat
panel.
* **Improvements**
* Chat panel now prioritizes pinned sessions and provides clearer
session initialization.
* Editor actions in chat messages are shown only when relevant document
information is present.
* Toolbar and chat content UI improved for clarity and usability.
* Scroll position is preserved and restored for pinned chat sessions.
* Session API updated to support more structured input types and new
session creation options.
* **Bug Fixes**
* Actions and toolbar buttons are now conditionally displayed based on
session and message state.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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