fix: resolve hover flickering caused by GPU layer destruction

- Preserve translateZ(0) on all hover/active transforms to prevent
  GPU compositing layer teardown/recreation cycle
- Lower body::before noise texture z-index to -1
- Add will-change: opacity to card spotlight pseudo-element
- Include backdrop-blur-linear in mobile performance override
- Replace transition-all with specific properties in BentoCard

src/components/ui/BentoCard.tsx

@@ -45,7 +45,8 @@ const baseClasses = `
   p-[var(--bento-padding)]
   bg-dark-900/70
   border border-dark-700/40
-  transition-all duration-300 ease-smooth
+  duration-300 ease-smooth
+  transition-[border-color,background-color,box-shadow,transform]
 `;
 
 const hoverClasses = `