feat: initialize voice-mobile React Native app with NativeWind v5

- Created new Expo app with SDK 54+ and Expo Router
- Installed and configured NativeWind v5 for Tailwind styling
- Upgraded voice-assistant to React 19 for consistency
- Kept voice-mobile outside workspace to avoid Metro bundler conflicts
- Disabled React Compiler experimental feature for stability

Setup includes:
- postcss.config.mjs with Tailwind PostCSS plugin
- global.css with Tailwind and NativeWind imports
- metro.config.js with NativeWind wrapper
- lightningcss pinned to 1.30.1 for stability

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

packages/voice-mobile/app/_layout.tsx

@@ -0,0 +1,25 @@
+import '../global.css';
+import { DarkTheme, DefaultTheme, ThemeProvider } from '@react-navigation/native';
+import { Stack } from 'expo-router';
+import { StatusBar } from 'expo-status-bar';
+import 'react-native-reanimated';
+
+import { useColorScheme } from '@/hooks/use-color-scheme';
+
+export const unstable_settings = {
+  anchor: '(tabs)',
+};
+
+export default function RootLayout() {
+  const colorScheme = useColorScheme();
+
+  return (
+    <ThemeProvider value={colorScheme === 'dark' ? DarkTheme : DefaultTheme}>
+      <Stack>
+        <Stack.Screen name="(tabs)" options={{ headerShown: false }} />
+        <Stack.Screen name="modal" options={{ presentation: 'modal', title: 'Modal' }} />
+      </Stack>
+      <StatusBar style="auto" />
+    </ThemeProvider>
+  );
+}