<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **Refactor**
- Streamlined and consolidated block and inline extension exports by removing multiple block-spec and inline extension arrays from public APIs.
- Reduced exported constants, types, and utility functions related to various block and embed features.
- Simplified the codebase by removing deprecated type guards, adapter extensions, and redundant extension groupings.
- **Chores**
- Cleaned up internal APIs by deleting unused exports, imports, and outdated code, enhancing maintainability.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **New Features**
- Introduced a preview mode for code blocks, allowing users to toggle between code and rendered previews (e.g., HTML output) directly within the editor.
- Added a preview toggle button to the code block toolbar for supported languages.
- Enabled dynamic rendering of code block previews using a shared WebContainer, allowing live HTML previews in an embedded iframe.
- Added HTML preview support with loading and error states for enhanced user feedback.
- Integrated the preview feature as a view extension provider for seamless framework support.
- **Bug Fixes**
- Improved toolbar layout and button alignment for a cleaner user interface.
- **Tests**
- Added end-to-end tests to verify the new code block preview functionality and language switching behavior.
- **Chores**
- Updated development server configuration to include enhanced security headers.
- Added a new runtime dependency for WebContainer support.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Saul-Mirone