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/QueueManagement/API/ScenicQueueAPI.swift

@@ -6,7 +6,7 @@
 //
 
 import Foundation
-import Observation
+import Combine
 
 /// 排队管理服务协议，定义列表、动作、设置、二维码和实时 token 能力。
 @MainActor
@@ -26,10 +26,9 @@ protocol ScenicQueueServing: AnyObject {
 }
 
 @MainActor
-@Observable
 /// 排队管理 API，封装 `/api/app/scenic-queue` 下的排队接口。
 final class ScenicQueueAPI {
-    @ObservationIgnored private let client: APIClient
+    private let client: APIClient
 
     /// 初始化排队管理 API，并注入共享网络客户端。
     init(client: APIClient) {