fix: increase PortalSelect z-index to prevent obscuring in dialogs

Increase the z-index of PortalSelect dropdown from z-20 to z-[1002] to
ensure select options are not obscured when used inside dialog/modal
containers that have higher z-index values.

fixes #27581

Signed-off-by: majiayu000 <1835304752@qq.com>

web/app/components/base/select/index.tsx

@@ -395,7 +395,7 @@ const PortalSelect: FC<PortalSelectProps> = ({
             )}
 
       </PortalToFollowElemTrigger>
-      <PortalToFollowElemContent className={`z-20 ${popupClassName}`}>
+      <PortalToFollowElemContent className={`z-[1002] ${popupClassName}`}>
         <div
           className={cn('max-h-60 overflow-auto rounded-xl border-[0.5px] border-components-panel-border bg-components-panel-bg px-1 py-1 text-base shadow-lg focus:outline-none sm:text-sm', popupInnerClassName)}
         >