perf: remove permanent GPU layer promotion from cards to fix flickering

Remove translateZ(0) from base states of .bento-card, .card, .glass
and their light theme variants. Remove transform-gpu from Card.tsx.
Change bentoFadeIn animation to end with transform:none instead of
translateY(0). GPU promotion now only occurs during hover/active
interactions, preventing Chrome from creating excessive compositing
layers that cause flickering with animated backgrounds.

src/components/data-display/Card/Card.tsx

@@ -12,8 +12,6 @@ const cardVariants = cva(
     'border border-dark-700/40 bg-dark-900/70',
     'rounded-[var(--bento-radius)]',
     'transition-[border-color,background-color,box-shadow,transform,opacity] duration-200',
-    // GPU acceleration
-    'transform-gpu',
     // Glass border inset
     'shadow-[inset_0_1px_0_0_rgba(255,255,255,0.05)]',
   ],