Add notification preferences UI and subscription verification on launch

- Add NotificationPreferencesScreen (Android) and NotificationPreferencesView (iOS)
- Add NotificationPreferencesViewModel for shared business logic
- Wire up notification preferences from ProfileScreen on both platforms
- Add subscription verification on app launch for iOS (StoreKit) and Android (Google Play Billing)
- Update SubscriptionApi to match Go backend endpoints (/subscription/purchase/)
- Update StoreKit Configuration with correct product IDs and pricing ($2.99/month, $27.99/year)
- Update Android placeholder prices to match App Store pricing
- Fix NotificationPreference model to match Go backend schema

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

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

docs/ANDROID_SUBSCRIPTION_PLAN.md

@@ -58,8 +58,8 @@ Replace stub implementation with full Google Play Billing:
 class BillingManager private constructor(private val context: Context) {
     // Product IDs (match Google Play Console)
     private val productIDs = listOf(
-        "com.example.mycrib.pro.monthly",
-        "com.example.mycrib.pro.annual"
+        "com.example.casera.pro.monthly",
+        "com.example.casera.pro.annual"
     )
 
     // BillingClient instance
@@ -270,7 +270,7 @@ These files show the iOS implementation to mirror:
 
 ## Notes
 
-- Product IDs must match Google Play Console: `com.example.mycrib.pro.monthly`, `com.example.mycrib.pro.annual`
+- Product IDs must match Google Play Console: `com.example.casera.pro.monthly`, `com.example.casera.pro.annual`
 - Backend endpoint `POST /subscription/verify-android/` already exists in SubscriptionApi
 - Testing requires Google Play Console setup with test products
 - Use Google's test cards for sandbox testing