fix: Use @State instead of @StateObject for @Observable AppViewModel

- Replace @StateObject with @State for @Observable conformance
- Remove unnecessary Task wrapper in init
- Call loadSetupStatus() synchronously since it's already @MainActor

readeck/UI/AppViewModel.swift

@@ -21,9 +21,7 @@ class AppViewModel {
         self.factory = factory
         setupNotificationObservers()
 
-        Task {
-            await loadSetupStatus()
-        }
+        loadSetupStatus()
     }
     
     private func setupNotificationObservers() {

readeck/UI/readeckApp.swift

@@ -10,7 +10,7 @@ import netfox
 
 @main
 struct readeckApp: App {
-    @StateObject private var appViewModel = AppViewModel()
+    @State private var appViewModel = AppViewModel()
     @StateObject private var appSettings = AppSettings()
     @Environment(\.scenePhase) private var scenePhase