TDD: SqlViewer renders collapsible CTE blocks with name/field-count/
test-status badges, shiki-highlighted SQL body (dangerouslySetInnerHTML),
per-field comments, and a vertical/horizontal layout toggle.
highlight.ts wraps shiki as a lazy singleton; tests mock it for
determinism (pattern mirrors mermaid.ts).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
