Add Quiz feature: 10-question quizzes with progressive scoring (max 40 pts)

- Quizzes table with questions, answer options, attempts, answers
- Question types: multiple_choice, exclusion, true_false, free_text
- Progressive scoring: [1,1,2,2,3,3,4,6,8,10] = max 40 per quiz
- Alpine.js countdown timer per question with auto-submit on timeout
- Admin: CRUD for quizzes + per-question editor, JSON export/import
- Child: quiz overview with best scores, question view, result breakdown
- Nav: Quiz link in child header and admin sidebar

resources/views/layouts/admin.blade.php

@@ -23,6 +23,9 @@
       <a href="{{ route('admin.questions.index') }}" class="flex items-center gap-3 px-3 py-2 rounded-lg {{ request()->routeIs('admin.questions.*') ? 'bg-violet-600 text-white' : 'text-slate-300 hover:bg-slate-800' }}">
         <span>❓</span> Fragen
       </a>
+      <a href="{{ route('admin.quizzes.index') }}" class="flex items-center gap-3 px-3 py-2 rounded-lg {{ request()->routeIs('admin.quizzes.*','admin.quiz-questions.*') ? 'bg-violet-600 text-white' : 'text-slate-300 hover:bg-slate-800' }}">
+        <span>🧠</span> Quizzes
+      </a>
       <a href="{{ route('admin.rewards.index') }}" class="flex items-center gap-3 px-3 py-2 rounded-lg {{ request()->routeIs('admin.rewards.*') ? 'bg-violet-600 text-white' : 'text-slate-300 hover:bg-slate-800' }}">
         <span>🎁</span> Belohnungen
       </a>

resources/views/layouts/child.blade.php

@@ -13,6 +13,7 @@
     </a>
     <div class="flex items-center gap-4">
       <a href="{{ route('learn.subjects') }}" class="text-sm font-medium text-slate-600 hover:text-indigo-600">Lernen</a>
+      <a href="{{ route('quiz.index') }}" class="text-sm font-medium text-slate-600 hover:text-indigo-600">🧠 Quiz</a>
       <a href="{{ route('rewards.index') }}" class="text-sm font-medium text-slate-600 hover:text-indigo-600">🪙 Belohnungen</a>
       <a href="{{ route('reference.index') }}" class="text-sm font-medium text-slate-600 hover:text-indigo-600">💡 Erinnerung</a>
       <div class="flex items-center gap-1 bg-amber-100 text-amber-700 font-bold rounded-full px-3 py-1 text-sm">