fix(a11y): improve color contrast in mobile navigation

- Increased background opacity from bg-white/75 to bg-white/95
- Updated text colors to text-neutral-dark to meet 4.5:1 contrast ratio requirement

components/layout/MobileBottomNav.tsx

@@ -95,7 +95,7 @@ export function MobileBottomNav({ navLinks, currentLocale }: MobileBottomNavProp
   return (
     <>
       <div className="md:hidden fixed bottom-0 left-0 right-0 z-[9999] px-2 pb-[calc(env(safe-area-inset-bottom)_+_12px)] pt-4 pointer-events-none flex justify-center">
-        <nav className="flex justify-between items-center bg-white/75 backdrop-blur-2xl border border-white/60 shadow-[0_8px_32px_rgba(0,0,0,0.12)] rounded-3xl p-1.5 pointer-events-auto w-full max-w-[480px]">
+        <nav className="flex justify-between items-center bg-white/95 backdrop-blur-2xl border border-white/60 shadow-[0_8px_32px_rgba(0,0,0,0.12)] rounded-3xl p-1.5 pointer-events-auto w-full max-w-[480px]">
           {items.map((item) => {
             const mappedUrl = item.url.startsWith('/') && !item.url.match(/^\/(en|de)/) 
               ? `/${currentLocale}${item.url}` 
@@ -144,7 +144,7 @@ export function MobileBottomNav({ navLinks, currentLocale }: MobileBottomNavProp
                   key={item.label}
                   onClick={() => setIsFlyoutOpen(!isFlyoutOpen)}
                   className={`relative flex flex-col items-center justify-center flex-1 h-[62px] transition-colors duration-300 select-none w-full focus:outline-none ${
-                    isActive ? 'text-primary-dark' : 'text-neutral-800 hover:text-neutral-900'
+                    isActive ? 'text-primary-dark' : 'text-neutral-dark hover:text-black'
                   }`}
                   style={{ WebkitTapHighlightColor: 'transparent', touchAction: 'manipulation' }}
                 >
@@ -159,7 +159,7 @@ export function MobileBottomNav({ navLinks, currentLocale }: MobileBottomNavProp
                 href={mappedUrl}
                 onClick={() => setIsFlyoutOpen(false)}
                 className={`relative flex flex-col items-center justify-center flex-1 h-[62px] transition-colors duration-300 select-none ${
-                  isActive ? 'text-primary-dark' : 'text-neutral-800 hover:text-neutral-900'
+                  isActive ? 'text-primary-dark' : 'text-neutral-dark hover:text-black'
                 }`}
                 style={{ WebkitTapHighlightColor: 'transparent', touchAction: 'manipulation' }}
               >