✨ feat(epic-4): chemins narratifs, easter eggs, challenge et contact

Epic 4: Chemins Narratifs, Challenge & Contact

Stories implementees:
- 4.1: Composant ChoiceCards pour choix narratifs binaires
- 4.2: Sequence d'intro narrative avec Le Bug
- 4.3: Chemins narratifs differencies avec useNarrativePath
- 4.4: Table easter_eggs et systeme de detection (API + composable)
- 4.5: Easter eggs UI (popup, notification, collection)
- 4.6: Page challenge avec puzzle de code
- 4.7: Page revelation "Monde de Code"
- 4.8: Page contact avec formulaire et stats

Fichiers crees:
- Frontend: ChoiceCards, IntroSequence, ZoneEndChoice, EasterEggPopup,
  CodePuzzle, ChallengeSuccess, CodeWorld, et pages intro/challenge/revelation
- API: EasterEggController, Model, Migration, Seeder

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

frontend/app/components/feature/EasterEggNotification.vue

@@ -0,0 +1,49 @@
+<template>
+  <Teleport to="body">
+    <Transition name="toast">
+      <div
+        v-if="visible"
+        class="fixed top-4 right-4 z-50 bg-sky-dark-50 border border-sky-accent/50 rounded-lg px-4 py-3 shadow-lg shadow-sky-accent/20 flex items-center gap-3"
+      >
+        <span class="text-2xl" aria-hidden="true">*</span>
+        <div>
+          <p class="font-ui font-semibold text-sky-accent">
+            {{ $t('easterEgg.found') }}
+          </p>
+          <p class="text-sm text-sky-text/60">
+            {{ $t('easterEgg.count', { found: foundCount, total: totalEasterEggs }) }}
+          </p>
+        </div>
+      </div>
+    </Transition>
+  </Teleport>
+</template>
+
+<script setup lang="ts">
+defineProps<{
+  visible: boolean
+}>()
+
+const progressionStore = useProgressionStore()
+const { availableEasterEggs } = useFetchEasterEggs()
+
+const totalEasterEggs = computed(() => availableEasterEggs.value.length || 8)
+const foundCount = computed(() => progressionStore.easterEggsFoundCount)
+</script>
+
+<style scoped>
+.toast-enter-active,
+.toast-leave-active {
+  transition: all 0.3s ease;
+}
+
+.toast-enter-from {
+  opacity: 0;
+  transform: translateX(100px);
+}
+
+.toast-leave-to {
+  opacity: 0;
+  transform: translateY(-20px);
+}
+</style>