Fix SplashScreen warning on subscription flow

- Add splashHidden flag to prevent double-hiding splash screen
- Add .catch() to preventAutoHideAsync to handle edge cases
- Fixes "No native splash screen registered" warning

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/_layout.tsx

@@ -15,7 +15,11 @@ import { useColorScheme } from '@/hooks/use-color-scheme';
 // Stripe publishable key (test mode) - must match backend STRIPE_PUBLISHABLE_KEY
 const STRIPE_PUBLISHABLE_KEY = 'pk_test_51P3kdqP0gvUw6M9C7ixPQHqbPcvga4G5kAYx1h6QXQAt1psbrC2rrmOojW0fTeQzaxD1Q9RKS3zZ23MCvjjZpWLi00eCFWRHMk';
 
-SplashScreen.preventAutoHideAsync();
+// Prevent auto-hide, ignore errors if splash not available
+SplashScreen.preventAutoHideAsync().catch(() => {});
+
+// Track if splash screen was hidden to prevent double-hiding
+let splashHidden = false;
 
 function RootLayoutNav() {
   const colorScheme = useColorScheme();
@@ -39,8 +43,11 @@ function RootLayoutNav() {
       return;
     }
 
-    // Hide splash screen safely
+    // Hide splash screen safely (only once)
+    if (!splashHidden) {
+      splashHidden = true;
       SplashScreen.hideAsync().catch(() => {});
+    }
 
     const inAuthGroup = segments[0] === '(auth)';