✨ feat(frontend): quiz bonus post-contact (Story 4.9)

- Add BonusQuiz.vue component with 7 randomized questions
- Add challenge-bonus.vue page with intro, quiz, and results
- Redirect to bonus quiz after successful contact form submission
- Add i18n translations for bonus.* (fr/en)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/app/pages/challenge-bonus.vue

@@ -0,0 +1,175 @@
+<template>
+  <div class="bonus-page min-h-screen bg-sky-dark flex flex-col items-center justify-center p-8 relative">
+    <!-- Bouton quitter (toujours visible) -->
+    <button
+      type="button"
+      class="absolute top-4 right-4 text-sky-text/60 hover:text-sky-text text-sm font-ui flex items-center gap-2 z-10"
+      @click="goHome"
+    >
+      <span>{{ $t('bonus.exit') }}</span>
+      <span aria-hidden="true">→</span>
+    </button>
+
+    <!-- Intro -->
+    <Transition name="fade" mode="out-in">
+      <div
+        v-if="showIntro"
+        key="intro"
+        class="max-w-lg text-center"
+      >
+        <img
+          src="/images/bug/bug-stage-5.svg"
+          alt="Le Bug"
+          class="w-24 h-24 mx-auto mb-6"
+        />
+
+        <h1 class="text-2xl font-ui font-bold text-sky-text mb-4">
+          {{ $t('bonus.waitingTitle') }}
+        </h1>
+
+        <p class="font-narrative text-lg text-sky-text/60 mb-8">
+          {{ $t('bonus.waitingMessage') }}
+        </p>
+
+        <div class="space-y-4">
+          <button
+            type="button"
+            class="w-full px-8 py-4 bg-sky-accent text-white font-ui font-semibold rounded-lg hover:bg-sky-accent/90 transition-colors"
+            @click="startQuiz"
+          >
+            {{ $t('bonus.playQuiz') }}
+          </button>
+
+          <button
+            type="button"
+            class="w-full px-8 py-4 border border-sky-dark-100 text-sky-text font-ui rounded-lg hover:bg-sky-dark-50 transition-colors"
+            @click="goHome"
+          >
+            {{ $t('bonus.noThanks') }}
+          </button>
+        </div>
+      </div>
+
+      <!-- Quiz -->
+      <div
+        v-else-if="showQuiz"
+        key="quiz"
+        class="w-full max-w-2xl"
+      >
+        <FeatureBonusQuiz @complete="handleQuizComplete" />
+      </div>
+
+      <!-- Résultat -->
+      <div
+        v-else-if="showResult"
+        key="result"
+        class="max-w-lg text-center"
+      >
+        <div class="text-6xl mb-4" aria-hidden="true">
+          {{ getResultEmoji }}
+        </div>
+
+        <h2 class="text-2xl font-ui font-bold text-sky-text mb-2">
+          {{ $t('bonus.resultTitle') }}
+        </h2>
+
+        <p class="text-4xl font-ui font-bold text-sky-accent mb-4">
+          {{ score }} / 5
+        </p>
+
+        <p class="font-narrative text-lg text-sky-text/60 mb-8">
+          {{ getResultMessage }}
+        </p>
+
+        <div class="space-y-4">
+          <button
+            type="button"
+            class="w-full px-8 py-4 bg-sky-accent text-white font-ui font-semibold rounded-lg hover:bg-sky-accent/90 transition-colors"
+            @click="playAgain"
+          >
+            {{ $t('bonus.playAgain') }}
+          </button>
+
+          <button
+            type="button"
+            class="w-full px-8 py-4 border border-sky-dark-100 text-sky-text font-ui rounded-lg hover:bg-sky-dark-50 transition-colors"
+            @click="goHome"
+          >
+            {{ $t('bonus.backHome') }}
+          </button>
+        </div>
+
+        <!-- Confirmation message envoyé -->
+        <p class="mt-8 text-sm text-sky-text/60">
+          {{ $t('bonus.messageConfirm') }}
+        </p>
+      </div>
+    </Transition>
+  </div>
+</template>
+
+<script setup lang="ts">
+definePageMeta({
+  layout: 'adventure',
+})
+
+const { t } = useI18n()
+const router = useRouter()
+const { setPageMeta } = useSeo()
+
+setPageMeta({
+  title: t('bonus.pageTitle'),
+  description: t('bonus.pageDescription'),
+})
+
+// États
+const showIntro = ref(true)
+const showQuiz = ref(false)
+const showResult = ref(false)
+const score = ref(0)
+
+function startQuiz() {
+  showIntro.value = false
+  showQuiz.value = true
+}
+
+function handleQuizComplete(finalScore: number) {
+  score.value = finalScore
+  showQuiz.value = false
+  showResult.value = true
+}
+
+function playAgain() {
+  showResult.value = false
+  showIntro.value = true
+  score.value = 0
+}
+
+function goHome() {
+  router.push('/')
+}
+
+const getResultEmoji = computed(() => {
+  if (score.value === 5) return '🏆'
+  if (score.value >= 3) return '🎉'
+  return '💪'
+})
+
+const getResultMessage = computed(() => {
+  if (score.value === 5) return t('bonus.perfectMessage')
+  if (score.value >= 3) return t('bonus.goodMessage')
+  return t('bonus.tryMessage')
+})
+</script>
+
+<style scoped>
+.fade-enter-active,
+.fade-leave-active {
+  transition: opacity 0.3s ease;
+}
+
+.fade-enter-from,
+.fade-leave-to {
+  opacity: 0;
+}
+</style>