✨ 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/stores/progression.ts

@@ -13,6 +13,7 @@ export interface ProgressionState {
   contactUnlocked: boolean
   choices: Record<string, string>
   consentGiven: boolean | null
+  introSeen: boolean
 }
 
 const NARRATOR_STAGE_THRESHOLDS = [0, 20, 40, 60, 80]
@@ -81,6 +82,7 @@ export const useProgressionStore = defineStore('progression', {
     contactUnlocked: false,
     choices: {},
     consentGiven: null,
+    introSeen: false,
   }),
 
   getters: {
@@ -93,6 +95,8 @@ export const useProgressionStore = defineStore('progression', {
     hasExistingProgress: (state) => state.visitedSections.length > 0 || state.hero !== null,
 
     narratorStage: (state) => calculateNarratorStage(state.completionPercent),
+
+    easterEggsFoundCount: (state) => state.easterEggsFound.length,
   },
 
   actions: {
@@ -124,6 +128,10 @@ export const useProgressionStore = defineStore('progression', {
       }
     },
 
+    markEasterEggFound(slug: string) {
+      this.findEasterEgg(slug)
+    },
+
     completeChallenge() {
       this.challengeCompleted = true
     },
@@ -136,6 +144,10 @@ export const useProgressionStore = defineStore('progression', {
       this.choices[choiceId] = value
     },
 
+    setIntroSeen(seen: boolean) {
+      this.introSeen = seen
+    },
+
     setConsent(given: boolean) {
       this.consentGiven = given
       if (given) {