SDK 53+ removed push notification support from Expo Go, causing the
module to throw at require-time. The static import in notifications.ts
propagated the error to _layout.tsx and both tab screens, making expo-
router report missing default exports and crash the app.
Switch to a try/catch require() so the module initialises safely in
Expo Go (Notifications stays null, all functions become no-ops) while
still working correctly in EAS / development builds.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>