fix(mobile): migrate to Expo SDK 54, replace NativeWind with StyleSheet

- Update package.json to Expo ~54.0.35, expo-router ~6.0.24, RN 0.81.5
- Remove NativeWind/Tailwind dependencies
- Fix babel.config.js: presets babel-preset-expo only
- Rewrite all screens with StyleSheet.create (no className)
- Add lucide-react-native + react-native-svg
- Export design tokens C from _layout.tsx for shared usage
- Install node_modules (702 packages)

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

memento-mobile/app/(tabs)/_layout.tsx

@@ -1,55 +1,22 @@
 import { Tabs } from 'expo-router'
 import { BookOpen, Search, Home, User } from 'lucide-react-native'
+import { C } from '../_layout'
 
 export default function TabsLayout() {
   return (
     <Tabs
       screenOptions={{
         headerShown: false,
-        tabBarActiveTintColor: '#A47148',
-        tabBarInactiveTintColor: '#8A8A82',
-        tabBarStyle: {
-          backgroundColor: '#FAFAF8',
-          borderTopColor: '#E8E6E0',
-          borderTopWidth: 1,
-          paddingBottom: 4,
-          height: 60,
-        },
-        tabBarLabelStyle: {
-          fontSize: 10,
-          fontWeight: '600',
-          marginTop: -2,
-        },
+        tabBarActiveTintColor: C.brand,
+        tabBarInactiveTintColor: C.concrete,
+        tabBarStyle: { backgroundColor: C.paper, borderTopColor: C.border, borderTopWidth: 1, paddingBottom: 4, height: 60 },
+        tabBarLabelStyle: { fontSize: 10, fontWeight: '600', marginTop: -2 },
       }}
     >
-      <Tabs.Screen
-        name="home"
-        options={{
-          title: 'Accueil',
-          tabBarIcon: ({ color, size }) => <Home size={size} color={color} />,
-        }}
-      />
-      <Tabs.Screen
-        name="notebooks"
-        options={{
-          title: 'Carnets',
-          tabBarIcon: ({ color, size }) => <BookOpen size={size} color={color} />,
-        }}
-      />
-      <Tabs.Screen
-        name="search"
-        options={{
-          title: 'Recherche',
-          tabBarIcon: ({ color, size }) => <Search size={size} color={color} />,
-        }}
-      />
-      <Tabs.Screen
-        name="profile"
-        options={{
-          title: 'Profil',
-          tabBarIcon: ({ color, size }) => <User size={size} color={color} />,
-        }}
-      />
+      <Tabs.Screen name="home" options={{ title: 'Accueil', tabBarIcon: ({ color, size }) => <Home size={size} color={color} /> }} />
+      <Tabs.Screen name="notebooks" options={{ title: 'Carnets', tabBarIcon: ({ color, size }) => <BookOpen size={size} color={color} /> }} />
+      <Tabs.Screen name="search" options={{ title: 'Recherche', tabBarIcon: ({ color, size }) => <Search size={size} color={color} /> }} />
+      <Tabs.Screen name="profile" options={{ title: 'Profil', tabBarIcon: ({ color, size }) => <User size={size} color={color} /> }} />
     </Tabs>
   )
 }