To close [BS-2870](https://linear.app/affine-design/issue/BS-2870/支持识别-和-[-包裹内容为公式)
## Add Markdown Preprocessor Extension and Enhanced LaTeX Support
### Markdown Preprocessor Extension
This PR introduces a new preprocessor extension for Markdown adapters that allows preprocessing of content before conversion:
Adds a new PreprocessorManager for handling text transformations
Introduces extensible preprocessor interface that supports different processing levels (block/slice/doc)
Integrates preprocessor extension into the existing Markdown adapter workflow
### LaTeX Support Enhancement
Extends LaTeX support to handle both traditional and alternative syntax:
Adds support for backslash LaTeX syntax:
Block math: ```\[...\] ``` alongside existing ```$$...$$```
Inline math: ```\(...\) ``` alongside existing ```$...$```
Implements LaTeX preprocessor to standardize syntax before conversion
Updates tests to cover both syntax variants
### TL;DR
Moved image proxy middleware and adapter extensions to their respective packages and introduced a new spec provider for adapter registration.
### What changed?
- Relocated `defaultImageProxyMiddleware` from blocks to `@blocksuite/affine-block-image`
- Moved `PresentTool` from fragment-frame-panel to block-frame
- Created new adapter extension specs for HTML, Markdown, and Notion HTML
- Introduced a spec provider pattern for adapter registration
- Removed direct transformer references from RootService
- Updated imports across affected files to use new locations
### How to test?
1. Verify image proxy functionality works in exports and imports
2. Test HTML, Markdown, and Notion HTML adapters still function correctly
3. Confirm presentation mode works with the relocated PresentTool
4. Check that all file import/export operations continue to work as expected
### Why make this change?
This reorganization improves code modularity by placing features in their logical packages and introduces a more maintainable pattern for adapter registration. The spec provider pattern makes it easier to manage and extend adapter functionality while reducing coupling between components.
