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/ViewModels/TaskCloudFileSelectionViewModel.swift

@@ -6,7 +6,7 @@
 //
 
 import Foundation
-import Observation
+import Combine
 
 /// 云盘文件类型筛选实体，表示发布任务选择附件时的过滤方式。
 enum TaskCloudFileFilter: Int, CaseIterable, Identifiable {
@@ -31,18 +31,17 @@ enum TaskCloudFileFilter: Int, CaseIterable, Identifiable {
 
 /// 云盘文件选择 ViewModel，负责目录浏览、筛选、分页和附件选择。
 @MainActor
-@Observable
-final class TaskCloudFileSelectionViewModel {
-    var path: [CloudDriveFile] = [CloudDriveFile(id: 0, name: "云盘")]
-    var files: [CloudDriveFile] = []
-    var total = 0
-    var page = 1
-    var searchText = ""
-    var selectedFilter: TaskCloudFileFilter = .all
-    var selectedFiles: [CloudDriveFile] = []
-    var isLoading = false
-    var isLoadingMore = false
-    var errorMessage: String?
+final class TaskCloudFileSelectionViewModel: ObservableObject {
+    @Published var path: [CloudDriveFile] = [CloudDriveFile(id: 0, name: "云盘")]
+    @Published var files: [CloudDriveFile] = []
+    @Published var total = 0
+    @Published var page = 1
+    @Published var searchText = ""
+    @Published var selectedFilter: TaskCloudFileFilter = .all
+    @Published var selectedFiles: [CloudDriveFile] = []
+    @Published var isLoading = false
+    @Published var isLoadingMore = false
+    @Published var errorMessage: String?
 
     private let pageSize = 20