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/Home/ViewModels/HomeViewModel.swift

@@ -6,13 +6,12 @@
 //
 
 import Foundation
-import Observation
+import Combine
 
 @MainActor
-@Observable
 /// 首页 ViewModel，根据当前角色权限构建首页菜单列表。
-final class HomeViewModel {
-    private(set) var menuItems: [HomeMenuItem] = []
+final class HomeViewModel: ObservableObject {
+    @Published private(set) var menuItems: [HomeMenuItem] = []
 
     /// 菜单排序权重，与旧工程和 Android 端保持一致。
     private let preferredOrder: [String] = [