feat: add browser language auto-detection

- Enhance LanguageContext with automatic browser language detection:
  - Check localStorage first for saved user preference
  - If no saved preference, detect browser language using navigator.language
  - Fallback to 'en' if browser language detection fails
  - Korean language detected if browser language starts with 'ko'
  - All other languages default to English

- Language detection priority:
  1. Saved preference in localStorage (user's explicit choice)
  2. Browser language detection (automatic)
  3. Default to English (fallback)

- Benefits:
  - Better user experience for Korean users
  - Automatic language selection on first visit
  - Respects user's browser language preferences
  - Maintains existing localStorage functionality
  - No breaking changes to existing behavior

Author: mmaxence

src/components/ui/PageHero.tsx

@@ -48,7 +48,7 @@ export function PageHero({
           initial={{ opacity: 0, y: 30 }}
           animate={{ opacity: 1, y: 0 }}
           transition={{ duration: 0.8, delay: 0.2, ease: 'easeOut' }}
-          className="text-5xl md:text-7xl font-bold mb-6 bg-gradient-to-r from-white to-muted-foreground bg-clip-text text-transparent"
+          className="text-5xl md:text-7xl font-bold mb-6 bg-gradient-to-r from-white to-muted-foreground bg-clip-text"
         >
           <BlurReveal duration={600}>
             {title}

src/contexts/LanguageContext.tsx

@@ -661,6 +661,11 @@ export const LanguageProvider = ({ children }: { children: ReactNode }) => {
     const savedLanguage = localStorage.getItem('language') as Language;
     if (savedLanguage && (savedLanguage === 'en' || savedLanguage === 'ko')) {
       setLanguage(savedLanguage);
+    } else {
+      // Auto-detect browser language if no saved preference
+      const browserLanguage = navigator.language || navigator.languages?.[0] || 'en';
+      const detectedLanguage = browserLanguage.startsWith('ko') ? 'ko' : 'en';
+      setLanguage(detectedLanguage);
     }
   }, []);