Implement bank transfer app flows

Thijooree iOS/ViewModels/AppViewModel.swift

@@ -0,0 +1,59 @@
+import Foundation
+import Observation
+
+@Observable
+final class AppViewModel {
+
+    enum Route: Equatable {
+        case onboarding
+        case login
+        case lock
+        case home
+    }
+
+    private(set) var route: Route
+
+    init() {
+        route = AppViewModel.initialRoute()
+    }
+
+    // MARK: - Route transitions (called by child views)
+
+    func completeOnboarding() {
+        UserDefaults.standard.set(true, forKey: "onboarding_done")
+        route = .login
+    }
+
+    func loginSucceeded() {
+        route = AppViewModel.requiresLock() ? .lock : .home
+    }
+
+    func unlock() {
+        route = .home
+    }
+
+    func lock() {
+        route = .lock
+    }
+
+    func logout() {
+        route = .login
+    }
+
+    // MARK: - Private
+
+    private static func initialRoute() -> Route {
+        guard UserDefaults.standard.bool(forKey: "onboarding_done") else {
+            return .onboarding
+        }
+        guard CredentialStore.shared.hasAnyCredentials() else {
+            return .login
+        }
+        return requiresLock() ? .lock : .home
+    }
+
+    private static func requiresLock() -> Bool {
+        let method = UserDefaults.standard.string(forKey: "security_method") ?? ""
+        return !method.isEmpty && method != "none"
+    }
+}