Feature Settings Module

@MainActor
@Observable
class SettingsViewModel {
    var currentTheme: UserThemePreference
    var shareDiagnostics: Bool
    var notificationsEnabled: Bool
    var isSubscribed: Bool
    
    func updateTheme(_ theme: UserThemePreference) async
    func toggleDiagnostics(_ enabled: Bool) async
    func signOut() async
}

@MainActor
@Observable
class PaywallViewModel {
    var offerings: [PaymentsOffering]
    var isLoading: Bool
    var error: String?
    
    func purchase(productID: String) async
    func restorePurchases() async
}

// 1. Add to Settings model
@Model
class Settings {
    var theme: UserThemePreference
    var shareDiagnostics: Bool
    var autoSaveChats: Bool  // New setting
}

// 2. Add to ViewModel
@Observable
class SettingsViewModel {
    var autoSaveChats: Bool
    
    func toggleAutoSave(_ enabled: Bool) async {
        autoSaveChats = enabled
        await settingsRepository.update(autoSaveChats: enabled)
    }
}

// 3. Add to UI
Toggle("Auto-save Chats", isOn: $viewModel.autoSaveChats)
    .onChange(of: viewModel.autoSaveChats) {
        Task { await viewModel.toggleAutoSave($0) }
    }

// In PaywallView, modify features list:
let proFeatures = [
    "Unlimited AI messages",
    "Access to GPT-4 and Claude",
    "Priority support",
    "Early access to features",
    "Custom AI personas"  // Add your feature
]

// 1. Add color set in DesignSystemColors.xcassets
// 2. Add case to UserThemePreference
public enum UserThemePreference: String, Codable {
    case system, light, dark, aurora, obsidian
    case custom  // New theme
}

// 3. Update DSColors to map your theme
// 4. Add to theme picker in Settings