fix(listview): match search top padding to left/right for consistency

SearchRow top padding was 0 while left/right was sizeUnit*2 (8px).
Make them equal so the search input has uniform breathing room.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

superset-frontend/src/components/ListView/Filters/CompactSelectPanel.tsx

@@ -66,7 +66,7 @@ const PanelContainer = styled.div`
 
 const SearchRow = styled.div`
   ${({ theme }) => css`
-    padding: 0 ${theme.sizeUnit * 2}px ${theme.paddingXXS}px;
+    padding: ${theme.sizeUnit * 2}px ${theme.sizeUnit * 2}px ${theme.paddingXXS}px;
   `}
 `;