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/App/State/PermissionContext.swift

@@ -6,15 +6,14 @@
 //
 
 import Foundation
-import Observation
+import Combine
 
 @MainActor
-@Observable
 /// 权限上下文状态中心，保存角色权限、当前角色和扁平化权限 URI。
-final class PermissionContext {
-    private(set) var rolePermissions: [RolePermissionResponse] = []
-    private(set) var permissionURIs: Set<String> = []
-    var currentRole: RoleInfo?
+final class PermissionContext: ObservableObject {
+    @Published private(set) var rolePermissions: [RolePermissionResponse] = []
+    @Published private(set) var permissionURIs: Set<String> = []
+    @Published var currentRole: RoleInfo?
 
     /// 替换角色权限列表，并尽量按缓存角色 ID 保持当前角色。
     func replaceRolePermissions(_ rolePermissions: [RolePermissionResponse], currentRoleId: Int? = nil) {