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/code-toolbar/components/code-toolbar.ts

@@ -30,7 +30,6 @@ export class AffineCodeToolbar extends WithDisposable(LitElement) {
       padding: 4px;
       margin: 0;
       display: flex;
-      justify-content: flex-end;
     }
 
     .code-toolbar-button {
@@ -39,6 +38,10 @@ export class AffineCodeToolbar extends WithDisposable(LitElement) {
       box-shadow: var(--affine-shadow-1);
       border-radius: 4px;
     }
+
+    .copy-code {
+      margin-left: auto;
+    }
   `;
 
   private _currentOpenMenu: AbortController | null = null;