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>

composeApp/src/commonMain/kotlin/com/example/casera/ui/subscription/UpgradeFeatureScreen.kt

@@ -253,8 +253,8 @@ private fun SubscriptionProductsSection(
         // Monthly Option
         SubscriptionProductCard(
             productId = "com.example.casera.pro.monthly",
-            name = "MyCrib Pro Monthly",
-            price = "$4.99/month",
+            name = "Casera Pro Monthly",
+            price = "$2.99/month",
             description = "Billed monthly",
             savingsBadge = null,
             isSelected = false,
@@ -265,10 +265,10 @@ private fun SubscriptionProductsSection(
         // Annual Option
         SubscriptionProductCard(
             productId = "com.example.casera.pro.annual",
-            name = "MyCrib Pro Annual",
-            price = "$39.99/year",
+            name = "Casera Pro Annual",
+            price = "$27.99/year",
             description = "Billed annually",
-            savingsBadge = "Save 33%",
+            savingsBadge = "Save 22%",
             isSelected = false,
             isProcessing = isProcessing,
             onSelect = { onProductSelected("com.example.casera.pro.annual") }