从 iOS 17 Observation 迁移至 iOS 16 兼容的 Combine 架构

将最低部署版本降至 iOS 16，以 ObservableObject 替换 @Observable，新增导航与 UI 兼容层，并补充登录冒烟 UI 测试。

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

suixinkan/Features/Tasks/Views/TaskDetailView.swift

@@ -9,14 +9,14 @@ import SwiftUI
 
 /// 任务详情页面，展示任务基础信息、关联订单和任务结果。
 struct TaskDetailView: View {
-    @Environment(TaskAPI.self) private var taskAPI
-    @Environment(ToastCenter.self) private var toastCenter
+    @Environment(\.taskAPI) private var taskAPI
+    @EnvironmentObject private var toastCenter: ToastCenter
     @Environment(\.globalLoading) private var globalLoading
 
     let taskId: Int
     let summary: PhotographerTaskItem?
 
-    @State private var viewModel = TaskDetailViewModel()
+    @StateObject private var viewModel = TaskDetailViewModel()
 
     var body: some View {
         ScrollView {