feat: App mobile Expo + API mobile dédiée

memento-mobile/ (Expo + React Native + expo-router):
- Auth: login email/password → Bearer token (expo-secure-store)
- Layout: guard auth → redirect /(auth)/login ou /(tabs)/home
- Tabs: Accueil, Carnets, Recherche, Profil
- Screens: login, home (recent notes + quick actions), notebooks list,
  note viewer (WebView HTML), search (texte), notebook detail, profile
- Design: tokens brand-accent (#A47148), ink, concrete, paper, border
- lib/config.ts: API_URL dev/prod configurable
- lib/api.ts: apiFetch avec Bearer token automatique
- lib/store.ts: Zustand auth store (login/logout/restore)

memento-note/ (API mobile dédiée):
- lib/mobile-auth.ts: createMobileToken / verifyMobileToken (HMAC-SHA256, 90j)
- POST /api/mobile/auth/login: email+password → token + user
- GET /api/mobile/auth/me: valider token, retourner profil
- GET /api/mobile/notebooks: liste carnets avec nb notes
- GET /api/mobile/notes: notes récentes (filtre par carnet optionnel)
- GET /api/mobile/notes/[id]: contenu complet d'une note
- GET /api/mobile/search: recherche fulltext titre+contenu

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

memento-mobile/package.json

@@ -0,0 +1,34 @@
+{
+  "name": "memento-mobile",
+  "version": "1.0.0",
+  "main": "expo-router/entry",
+  "scripts": {
+    "start": "expo start",
+    "android": "expo start --android",
+    "ios": "expo start --ios",
+    "build:android": "eas build --platform android",
+    "build:ios": "eas build --platform ios"
+  },
+  "dependencies": {
+    "expo": "~52.0.0",
+    "expo-router": "~4.0.0",
+    "expo-status-bar": "~2.0.1",
+    "expo-secure-store": "~14.0.0",
+    "expo-font": "~13.0.2",
+    "expo-splash-screen": "~0.29.18",
+    "react": "18.3.1",
+    "react-native": "0.76.7",
+    "react-native-safe-area-context": "4.12.0",
+    "react-native-screens": "~4.4.0",
+    "react-native-webview": "13.12.5",
+    "@react-native-async-storage/async-storage": "1.23.1",
+    "nativewind": "^4.1.23",
+    "tailwindcss": "^3.4.0",
+    "zustand": "^5.0.2"
+  },
+  "devDependencies": {
+    "@babel/core": "^7.25.2",
+    "@types/react": "~18.3.12",
+    "typescript": "^5.3.3"
+  }
+}