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/App/State/AccountContext.swift

@@ -5,7 +5,7 @@
 //  Created by Codex on 2026/6/18.
 //
 
-import Observation
+import Combine
 
 /// 当前账号的基础资料实体，用于跨页面展示昵称、手机号和头像。
 struct AccountProfile: Codable, Equatable {
@@ -58,14 +58,13 @@ struct BusinessScope: Codable, Equatable, Identifiable {
 }
 
 @MainActor
-@Observable
 /// 账号上下文状态中心，保存当前账号资料和景区/门店作用域。
-final class AccountContext {
-    private(set) var profile: AccountProfile?
-    private(set) var scenicScopes: [BusinessScope] = []
-    private(set) var storeScopes: [BusinessScope] = []
-    var currentScenic: BusinessScope?
-    var currentStore: BusinessScope?
+final class AccountContext: ObservableObject {
+    @Published private(set) var profile: AccountProfile?
+    @Published private(set) var scenicScopes: [BusinessScope] = []
+    @Published private(set) var storeScopes: [BusinessScope] = []
+    @Published var currentScenic: BusinessScope?
+    @Published var currentStore: BusinessScope?
 
     /// 应用登录成功后写入账号资料。
     func applyLogin(profile: AccountProfile? = nil) {