phsl / new-api

Enhance table scrollbar visual design with lighter and thinner styling for better user experience.

Changes:
- Add custom scrollbar styling for .semi-table-body
- Set scrollbar dimensions to 6px width/height
- Apply lighter color using rgba(var(--semi-grey-2), 0.3) with 30% opacity
- Add hover effect with 50% opacity for better interaction feedback
- Use 2px border radius for smoother appearance
- Keep scrollbar track transparent for clean look
- Utilize Semi Design color variables for theme consistency

The new scrollbar design provides a more elegant and less intrusive horizontal scrolling experience across all data tables.