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/TaskCreateView.swift

@@ -11,14 +11,14 @@ import UniformTypeIdentifiers
 
 /// 发布任务页面，负责填写任务信息、选择附件并提交任务。
 struct TaskCreateView: View {
-    @Environment(AccountContext.self) private var accountContext
-    @Environment(TaskAPI.self) private var taskAPI
-    @Environment(OSSUploadService.self) private var ossUploadService
-    @Environment(ToastCenter.self) private var toastCenter
+    @EnvironmentObject private var accountContext: AccountContext
+    @Environment(\.taskAPI) private var taskAPI
+    @Environment(\.ossUploadService) private var ossUploadService
+    @EnvironmentObject private var toastCenter: ToastCenter
     @Environment(\.dismiss) private var dismiss
     @Environment(\.globalLoading) private var globalLoading
 
-    @State private var viewModel = TaskCreateViewModel()
+    @StateObject private var viewModel = TaskCreateViewModel()
     @State private var showOrderSelection = false
     @State private var showCloudSelection = false
     @State private var pickerItems: [PhotosPickerItem] = []
@@ -60,7 +60,7 @@ struct TaskCreateView: View {
                 }
             }
         }
-        .onChange(of: pickerItems) { _, items in
+        .onChange(of: pickerItems) { items in
             Task { await importPickerItems(items) }
         }
     }