Buy on StoreKit and Play Billing, then confirm with the backend (#78).

Native purchases replace RevenueCat. The app sends the signed transaction or Play token to /monetization/store/confirm/ so access is granted only after the store check.

llm-fe/ios/App/Podfile

@@ -1,6 +1,6 @@
 require_relative '../../node_modules/@capacitor/ios/scripts/pods_helpers'
 
-platform :ios, '14.0'
+platform :ios, '15.0'
 use_frameworks!
 
 # workaround to avoid Xcode caching of Pods that requires
@@ -15,6 +15,7 @@ def capacitor_pods
   pod 'CapacitorKeyboard', :path => '../../node_modules/@capacitor/keyboard'
   pod 'CapacitorPreferences', :path => '../../node_modules/@capacitor/preferences'
   pod 'CapacitorStatusBar', :path => '../../node_modules/@capacitor/status-bar'
+  pod 'NativeStoreBilling', :path => '../../plugins/native-store-billing'
 end
 
 target 'App' do