### TL;DR
For canvas elements, this PR adds placeholders during zooming operations to improve performance.
### What changed?
- Implemented placeholder rendering during zooming operations in the canvas renderer, but not only DOM.
- Added a `forceFullRender` property to the `GfxCompatibleInterface` to allow elements to opt out of placeholder rendering
- Set `forceFullRender = true` for connectors to ensure they always render properly, even during zooming
- Connected the turbo renderer to the viewport's zooming state to automatically switch between full and placeholder rendering
### Why make this change?
Rendering complex elements during zooming operations can cause performance issues and make the UI feel sluggish. Rendering connector label also leads to high cost DOM `set font` delays.
The turbo renderer improves performance by displaying simple placeholders for elements during zooming, while still rendering critical elements like connectors fully. This creates a smoother user experience while maintaining essential visual information.
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **New Features**
- Introduced a feature-flag-controlled "turbo" rendering mode that displays placeholder graphics during zooming for improved performance.
- Added the ability to override placeholder rendering for specific elements, ensuring full rendering when required.
- **Bug Fixes**
- Enhanced rendering logic to ensure connectors always render fully, even during zoom operations.
- **Documentation**
- Updated API documentation to reflect new properties related to rendering behavior.
- **Tests**
- Improved tests to verify correct rendering behavior for connectors.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Close [BS-3079](https://linear.app/affine-design/issue/BS-3079).
- Separate the create session logic from the `createMessage function`.
- Ensure the session is created before executing any chat or actions.
- Convert the `AIActions` into asynchronous functions.
- Transfer the update prompt name logic to the chat action.
- Introduce a networkSearch field in `AITextActionOptions`.
- Eliminate the redundant `LAST_ROOT_SESSION_ID`.
Closes: [BS-2909](https://linear.app/affine-design/issue/BS-2909/新增highlighter)
### What's Changed!
Currently the highlighter tool is very similar to brush, but for the future, it's a standalone module.
* Added `Highlighter` element model
* Added `Highlighter` tool
* Added `Highlighter` entry to the global toolbar
doodlewind
