Wire all 7 learn pages to central translation system

All exercise pages now use useNativeLanguage() hook:
- Buttons show text in user's native language (Richtig→Dogru, etc.)
- Instructions translated (Geschafft→Bitti, Nochmal→Tekrar, etc.)
- wordInNative() available for vocab translations (needs data)

Pages updated: flashcards, quiz, type, listen, match, pronounce, story.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

studio-v2/app/learn/[unitId]/match/page.tsx

@@ -3,6 +3,7 @@
 import React, { useState, useEffect, useCallback, useMemo } from 'react'
 import { useParams, useRouter } from 'next/navigation'
 import { useTheme } from '@/lib/ThemeContext'
+import { useNativeLanguage } from '@/lib/useNativeLanguage'
 import { StarRating, accuracyToStars } from '@/components/gamification/StarRating'
 
 interface QAItem { id: string; question: string; answer: string }
@@ -13,6 +14,7 @@ export default function MatchPage() {
   const { unitId } = useParams<{ unitId: string }>()
   const router = useRouter()
   const { isDark } = useTheme()
+  const { t, wordInNative, nativeLang, isThirdLanguage } = useNativeLanguage()
 
   const [allItems, setAllItems] = useState<QAItem[]>([])
   const [isLoading, setIsLoading] = useState(true)