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/babel.config.js

@@ -1,9 +1,6 @@
 module.exports = function (api) {
   api.cache(true);
   return {
-    presets: [
-      ['babel-preset-expo', { jsxImportSource: 'nativewind' }],
-      'nativewind/babel',
-    ],
+    presets: ['babel-preset-expo'],
   };
 };