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/ScenicPermission/ViewModels/ScenicSelectionViewModel.swift

@@ -7,7 +7,7 @@
 
 import CoreLocation
 import Foundation
-import Observation
+import Combine
 
 /// 景区选择展示实体，表示列表中的一个可切换景区。
 struct ScenicSelectionItem: Equatable, Identifiable {
@@ -51,13 +51,12 @@ struct ScenicSelectionItem: Equatable, Identifiable {
 }
 
 @MainActor
-@Observable
 /// 景区选择 ViewModel，负责搜索、定位距离计算和切换景区持久化。
-final class ScenicSelectionViewModel {
-    var searchQuery = ""
-    var currentLocationText = "定位后获取最近景区"
-    var locationWarning: String?
-    private(set) var items: [ScenicSelectionItem] = []
+final class ScenicSelectionViewModel: ObservableObject {
+    @Published var searchQuery = ""
+    @Published var currentLocationText = "定位后获取最近景区"
+    @Published var locationWarning: String?
+    @Published private(set) var items: [ScenicSelectionItem] = []
 
     /// 返回按搜索关键词过滤后的景区列表。
     var filteredItems: [ScenicSelectionItem] {