Xcode 27: compila sin warnings y migra API deprecadas de SwiftUI

- Imports de CoreData que faltaban (MemberImportVisibility) en AccountsView,
  ImportDataView, ChartsContainerView y AddSourceView.
- Aislamiento MainActor: IsolatedDefaultValues en el target de la app,
  LinearGradient @MainActor, WatchSyncMessage nonisolated, closures de
  ReviewPromptService/MonthlyCheckInStore/AppIntents.
- Warnings de valores sin usar (SnapshotGapDetector, DashboardLayoutStore,
  OnboardingView, GoalEditorView, CoreDataStack, SettingsViewModel).
- foregroundColor→foregroundStyle, cornerRadius→clipShape,
  navigationBarLeading/Trailing→topBarLeading/Trailing,
  Task.sleep(nanoseconds:)→sleep(for:), NavigationLink(isActive:)→
  navigationDestination(isPresented:).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01F1u4K16xy7eQVtgsYNZ9Vn

PortfolioJournal/Utilities/DashboardLayoutStore.swift

@@ -74,7 +74,7 @@ enum DashboardLayoutStore {
 
         var merged: [DashboardSectionConfig] = []
         for config in decoded {
-            if let section = DashboardSection(rawValue: config.id) {
+            if DashboardSection(rawValue: config.id) != nil {
                 merged.append(config)
             } else {
                 continue