Added remark-gfm plugin to enable GitHub Flavored Markdown support,
which includes proper table rendering. Updated all ReactMarkdown
usages with table styling components:
- ChatPanel (source and notebook chat)
- StreamingResponse (search/ask results)
- SourceInsightDialog
- SourceDetailContent
- TransformationPlayground
Tables now render with proper borders, headers with background,
and horizontal scroll for wide tables.
6e8f46420a