feat(controlled): 实现设备激活与安全认证流程

- 添加API客户端、加密存储和provision/token激活逻辑
- WebSocket改用Bearer令牌认证，移除REGISTER请求
- 设备ID改为服务端下发，支持令牌刷新和强制下线处理
- 新增deviceSecret加密存储和accessToken自动刷新
- 更新设备ID获取方式为出厂SN，添加安全存储依赖

webrtc_controller_ios/web_rtc_controller_ios/Views/LoginView.swift

@@ -0,0 +1,51 @@
+import SwiftUI
+
+/// 登录界面：输入用户名/密码，调用 ViewModel.login 保存令牌后进入主界面。
+struct LoginView: View {
+    @ObservedObject var viewModel: ControllerViewModel
+
+    @State private var username: String = ""
+    @State private var password: String = ""
+
+    var body: some View {
+        NavigationView {
+            Form {
+                Section("账号登录") {
+                    TextField("用户名", text: $username)
+                        .textInputAutocapitalization(.never)
+                        .autocorrectionDisabled()
+                    SecureField("密码", text: $password)
+                }
+
+                if let err = viewModel.loginError, !err.isEmpty {
+                    Section {
+                        Text(err).foregroundColor(.red)
+                    }
+                }
+
+                Section {
+                    Button {
+                        Task {
+                            await viewModel.login(username: username, password: password)
+                        }
+                    } label: {
+                        HStack {
+                            Spacer()
+                            if viewModel.isLoggingIn {
+                                ProgressView().padding(.trailing, 8)
+                            }
+                            Text(viewModel.isLoggingIn ? "登录中..." : "登录")
+                                .font(.system(size: 15, weight: .semibold))
+                            Spacer()
+                        }
+                    }
+                    .disabled(viewModel.isLoggingIn || username.isEmpty || password.isEmpty)
+                } footer: {
+                    Text("登录后才能连接信令服务器并发起远程控制。账号由服务端统一创建与管控。")
+                }
+            }
+            .navigationTitle("WebRTC 控制端")
+        }
+        .navigationViewStyle(.stack)
+    }
+}