fix(tour): remove duplicate overlay on center-placed tour steps

Joyride's spotlight already renders a full-screen overlay via boxShadow.
The centered TourTooltip was adding its own bg-black/55 overlay on top,
causing double-darkened backgrounds. Removed the redundant overlay div.

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

Author: waleedlatif1

apps/sim/components/emcn/components/tour-tooltip/tour-tooltip.tsx

@@ -169,7 +169,6 @@ function TourTooltip({
   if (isCentered) {
     return createPortal(
       <div className='fixed inset-0 z-[10000300] flex items-center justify-center'>
-        <div className='absolute inset-0 bg-black/55' />
         <div
           className={cn(
             cardClasses,