feat(editor): block comment extension (#12980)

#### PR Dependency Tree


* **PR #12980** 👈

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

@@ -1,4 +1,5 @@
 import { scrollbarStyle } from '@blocksuite/affine-shared/styles';
+import { unsafeCSSVarV2 } from '@blocksuite/affine-shared/theme';
 import { css } from 'lit';
 
 export const codeBlockStyles = css`
@@ -20,6 +21,10 @@ export const codeBlockStyles = css`
     padding: 12px;
   }
 
+  .affine-code-block-container.highlight-comment {
+    outline: 2px solid ${unsafeCSSVarV2('block/comment/highlightUnderline')};
+  }
+
   ${scrollbarStyle('.affine-code-block-container rich-text')}
 
   .affine-code-block-container .inline-editor {