feat(editor): support preview mode in code block (#11805)

<!-- 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 -->

blocksuite/affine/blocks/code/src/effects.ts

@@ -5,6 +5,7 @@ import {
 } from './code-toolbar';
 import { AffineCodeToolbar } from './code-toolbar/components/code-toolbar';
 import { LanguageListButton } from './code-toolbar/components/lang-button';
+import { PreviewButton } from './code-toolbar/components/preview-button';
 import { AffineCodeUnit } from './highlight/affine-code-unit';
 
 export function effects() {
@@ -13,12 +14,14 @@ export function effects() {
   customElements.define(AFFINE_CODE_TOOLBAR_WIDGET, AffineCodeToolbarWidget);
   customElements.define('affine-code-unit', AffineCodeUnit);
   customElements.define('affine-code', CodeBlockComponent);
+  customElements.define('preview-button', PreviewButton);
 }
 
 declare global {
   interface HTMLElementTagNameMap {
     'language-list-button': LanguageListButton;
     'affine-code-toolbar': AffineCodeToolbar;
+    'preview-button': PreviewButton;
     [AFFINE_CODE_TOOLBAR_WIDGET]: AffineCodeToolbarWidget;
   }
 }