Implement Android subscription system with freemium limitations

Major subscription system implementation for Android:

BillingManager (Android):
- Full Google Play Billing Library integration
- Product loading, purchase flow, and acknowledgment
- Backend verification via APILayer.verifyAndroidPurchase()
- Purchase restoration for returning users
- Error handling and connection state management

SubscriptionHelper (Shared):
- New limit checking methods: isResidencesBlocked(), isTasksBlocked(),
  isContractorsBlocked(), isDocumentsBlocked()
- Add permission checks: canAddProperty(), canAddTask(),
  canAddContractor(), canAddDocument()
- Enforces freemium rules based on backend limitationsEnabled flag

Screen Updates:
- ContractorsScreen: Show upgrade prompt when contractors limit=0
- DocumentsScreen: Show upgrade prompt when documents limit=0
- ResidencesScreen: Show upgrade prompt when properties limit reached
- ResidenceDetailScreen: Show upgrade prompt when tasks limit reached

UpgradeFeatureScreen:
- Enhanced with feature benefits comparison
- Dynamic content from backend upgrade triggers
- Platform-specific purchase buttons

Additional changes:
- DataCache: Added O(1) lookup maps for ID resolution
- New minimal models (TaskMinimal, ContractorMinimal, ResidenceMinimal)
- TaskApi: Added archive/unarchive endpoints
- Added Google Billing Library dependency
- iOS SubscriptionCache and UpgradePromptView updates

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

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

composeApp/build.gradle.kts

@@ -52,6 +52,7 @@ kotlin {
 
 //            implementation(libs.ktor.client.logging)
             implementation(libs.kotlinx.coroutines.android)
+            implementation(libs.google.billing)
         }
         iosMain.dependencies {
             implementation(libs.ktor.client.darwin)