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/app/(tabs)/profile.tsx

@@ -0,0 +1,73 @@
+import { View, Text, TouchableOpacity, ScrollView, Alert } from 'react-native'
+import { SafeAreaView } from 'react-native-safe-area-context'
+import { LogOut, CreditCard, Globe } from 'lucide-react-native'
+import { useAuthStore } from '@/lib/store'
+
+const TIER_LABELS: Record<string, string> = {
+  FREE: 'Gratuit',
+  BASIC: 'Basic',
+  PRO: 'Pro',
+  BUSINESS: 'Business',
+  ENTERPRISE: 'Enterprise',
+}
+
+export default function ProfileScreen() {
+  const { user, logout } = useAuthStore()
+
+  const handleLogout = () => {
+    Alert.alert(
+      'Se déconnecter',
+      'Voulez-vous vraiment vous déconnecter ?',
+      [
+        { text: 'Annuler', style: 'cancel' },
+        { text: 'Déconnecter', style: 'destructive', onPress: logout },
+      ]
+    )
+  }
+
+  return (
+    <SafeAreaView className="flex-1 bg-paper">
+      <ScrollView className="flex-1 px-5">
+        <Text className="text-2xl font-serif italic text-ink pt-4 pb-6">Profil</Text>
+
+        {/* User info */}
+        <View className="bg-white border border-border rounded-2xl p-5 mb-4">
+          <View className="w-14 h-14 rounded-full bg-brand/10 items-center justify-center mb-3">
+            <Text className="text-2xl font-bold text-brand">
+              {user?.name?.[0]?.toUpperCase() ?? user?.email?.[0]?.toUpperCase() ?? '?'}
+            </Text>
+          </View>
+          <Text className="text-[17px] font-semibold text-ink">{user?.name ?? 'Utilisateur'}</Text>
+          <Text className="text-[13px] text-concrete mt-0.5">{user?.email}</Text>
+          {user?.tier && (
+            <View className="mt-3 self-start bg-brand/10 px-3 py-1 rounded-full">
+              <Text className="text-[11px] font-bold text-brand uppercase tracking-wider">
+                {TIER_LABELS[user.tier] ?? user.tier}
+              </Text>
+            </View>
+          )}
+        </View>
+
+        {/* Actions */}
+        <View className="bg-white border border-border rounded-2xl overflow-hidden mb-4">
+          <TouchableOpacity className="flex-row items-center gap-3 px-4 py-3.5 border-b border-border active:bg-border/20">
+            <CreditCard size={18} color="#8A8A82" />
+            <Text className="text-[15px] text-ink flex-1">Abonnement</Text>
+          </TouchableOpacity>
+          <TouchableOpacity className="flex-row items-center gap-3 px-4 py-3.5 active:bg-border/20">
+            <Globe size={18} color="#8A8A82" />
+            <Text className="text-[15px] text-ink flex-1">Ouvrir memento-note.com</Text>
+          </TouchableOpacity>
+        </View>
+
+        <TouchableOpacity
+          onPress={handleLogout}
+          className="bg-white border border-rose-200 rounded-2xl flex-row items-center gap-3 px-4 py-3.5 active:opacity-70"
+        >
+          <LogOut size={18} color="#e11d48" />
+          <Text className="text-[15px] text-rose-600 font-medium">Se déconnecter</Text>
+        </TouchableOpacity>
+      </ScrollView>
+    </SafeAreaView>
+  )
+}