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/_layout.tsx

@@ -2,7 +2,7 @@ import { useEffect } from 'react'
 import { Slot, useRouter, useSegments } from 'expo-router'
 import { SafeAreaProvider } from 'react-native-safe-area-context'
 import { StatusBar } from 'expo-status-bar'
-import { View, ActivityIndicator } from 'react-native'
+import { View, ActivityIndicator, StyleSheet } from 'react-native'
 import { useAuthStore } from '@/lib/store'
 
 export default function RootLayout() {
@@ -10,24 +10,19 @@ export default function RootLayout() {
   const router = useRouter()
   const segments = useSegments()
 
-  useEffect(() => {
-    restore()
-  }, [])
+  useEffect(() => { restore() }, [])
 
   useEffect(() => {
     if (loading) return
     const inAuth = segments[0] === '(auth)'
-    if (!user && !inAuth) {
-      router.replace('/(auth)/login')
-    } else if (user && inAuth) {
-      router.replace('/(tabs)/home')
-    }
+    if (!user && !inAuth) router.replace('/(auth)/login')
+    else if (user && inAuth) router.replace('/(tabs)/home')
   }, [user, loading, segments])
 
   if (loading) {
     return (
-      <View className="flex-1 items-center justify-center bg-paper">
-        <ActivityIndicator size="large" color="#A47148" />
+      <View style={s.loader}>
+        <ActivityIndicator size="large" color={C.brand} />
       </View>
     )
   }
@@ -39,3 +34,19 @@ export default function RootLayout() {
     </SafeAreaProvider>
   )
 }
+
+export const C = {
+  brand: '#A47148',
+  ink: '#1A1A18',
+  paper: '#FAFAF8',
+  concrete: '#8A8A82',
+  border: '#E8E6E0',
+  white: '#FFFFFF',
+  rose: '#e11d48',
+  roseBg: '#fff1f2',
+  roseBorder: '#fecdd3',
+}
+
+const s = StyleSheet.create({
+  loader: { flex: 1, alignItems: 'center', justifyContent: 'center', backgroundColor: C.paper },
+})