Migrate from iOS 17 Observation to iOS 16-compatible Combine architecture.

Lower deployment target to iOS 16, replace @Observable with ObservableObject, add navigation and UI compatibility shims, and include login smoke UI tests.

Co-authored-by: Cursor <cursoragent@cursor.com>

suixinkan/Features/Tasks/Views/TaskManagementView.swift

@@ -9,13 +9,13 @@ import SwiftUI
 
 /// 任务管理页面，展示任务列表、筛选条件和发布任务入口。
 struct TaskManagementView: View {
-    @Environment(AccountContext.self) private var accountContext
-    @Environment(RouterPath.self) private var router
-    @Environment(TaskAPI.self) private var taskAPI
-    @Environment(ToastCenter.self) private var toastCenter
+    @EnvironmentObject private var accountContext: AccountContext
+    @EnvironmentObject private var router: RouterPath
+    @Environment(\.taskAPI) private var taskAPI
+    @EnvironmentObject private var toastCenter: ToastCenter
     @Environment(\.globalLoading) private var globalLoading
 
-    @State private var viewModel = TaskManagementViewModel()
+    @StateObject private var viewModel = TaskManagementViewModel()
 
     var body: some View {
         ScrollView {
@@ -55,7 +55,7 @@ struct TaskManagementView: View {
                 }
             }
             .pickerStyle(.segmented)
-            .onChange(of: viewModel.selectedStatus) { _, _ in
+            .onChange(of: viewModel.selectedStatus) { _ in
                 Task { await reload(showLoading: true) }
             }