feat(ios): 添加远端视频录制功能并优化信令连接稳定性

- 新增 VideoRecorder 组件，支持 WebRTC 和自编码两种模式录制远端视频为 MP4
- 优化 SignalingClient 连接管理，修复 WebSocket 握手前 receive 导致的断开问题
- 重构控制面板 UI，支持统计信息折叠展开和录制控制按钮
- 添加录制状态指示、保存路径提示及断开自动取消录制逻辑
- 更新项目配置和文档，补充录制功能说明

webrtc_controller_ios/web_rtc_controller_ios/ViewModel/ControllerViewModel.swift

@@ -48,12 +48,14 @@ final class ControllerViewModel: NSObject, ObservableObject {
     // MARK: - UI 状态
 
     @Published var serverUrl: String = "wss://www.ttstd.com/signal"
-    @Published var targetDeviceId: String = ""
+    @Published var targetDeviceId: String = "981964879"
     @Published var statusText: String = "未连接"
     /// 是否显示控制界面（对应 Android 的 setupPanel/controlPanel 切换）
     @Published var isControlling: Bool = false
     @Published var isConnecting: Bool = false
     @Published var statsText: String = ""
+    /// 统计信息面板是否展开（默认收起，仅显示概要）
+    @Published var statsExpanded: Bool = false
     @Published var streamMode: StreamMode = .webrtc
     @Published var selectedResolution: ResolutionOption = ResolutionOption.all[0]
     /// 帧率档位：默认常用档位，收到被控端上报的 supported_fps 后以上报列表为准
@@ -65,6 +67,11 @@ final class ControllerViewModel: NSObject, ObservableObject {
     @Published var showAuthSheet: Bool = false
     @Published var alertMessage: String?
 
+    /// 是否正在录制远端视频
+    @Published var isRecording: Bool = false
+    /// 最近一次录制保存的文件路径（沙盒内）
+    @Published var lastRecordingPath: String?
+
     let myDeviceId: String = DeviceUtils.deviceId()
 
     // MARK: - UIKit 渲染视图（由 ViewModel 持有，SwiftUI 通过 Representable 嵌入）
@@ -77,6 +84,8 @@ final class ControllerViewModel: NSObject, ObservableObject {
     private var signalingClient: SignalingClient?
     private var webRTCClient: WebRTCClient?
     private let selfCodecDecoder = SelfCodecDecoder()
+    /// 远端视频录制器（MP4），跟随两种串流模式工作
+    private let videoRecorder = VideoRecorder()
 
     private var statsTimer: Timer?
     private var connectionStartTime: Date?
@@ -98,6 +107,24 @@ final class ControllerViewModel: NSObject, ObservableObject {
             guard let self, self.streamMode == .selfCodec, w > 0, h > 0 else { return }
             self.videoAspect = CGFloat(w) / CGFloat(h)
         }
+        // 自编码模式：把硬解出的 AVCC 帧回传给录制器写盘
+        selfCodecDecoder.onDecodedSampleBuffer = { [weak self] sample, isKey in
+            self?.videoRecorder.appendDecodedSampleBuffer(sample, isKey: isKey)
+        }
+        // 录制状态/结果回调
+        videoRecorder.onStateChange = { [weak self] state in
+            self?.isRecording = (state == .recording)
+        }
+        videoRecorder.onSaved = { [weak self] path in
+            self?.lastRecordingPath = path
+            self?.alertMessage = "录制已保存:\n\(path)"
+        }
+        videoRecorder.onSavedEmpty = { [weak self] in
+            self?.alertMessage = "未录到任何画面"
+        }
+        videoRecorder.onError = { [weak self] msg in
+            self?.alertMessage = "录制失败: \(msg)"
+        }
     }
 
     // MARK: - 连接 / 断开
@@ -134,6 +161,8 @@ final class ControllerViewModel: NSObject, ObservableObject {
 
     func disconnect() {
         stopStatsTimer()
+        videoRecorder.cancel()
+        isRecording = false
         selfCodecDecoder.setEnabled(false)
         webRTCClient?.close()
         webRTCClient = nil
@@ -225,6 +254,25 @@ final class ControllerViewModel: NSObject, ObservableObject {
         selfCodecDecoder.setEnabled(mode == .selfCodec)
     }
 
+    // MARK: - 录制
+
+    /// 开始录制远端画面（WebRTC 与自编码两种模式均支持）。
+    /// 需在已连接后调用；若尚未建立连接会提示。
+    func startRecording() {
+        guard isControlling else {
+            alertMessage = "请先连接被控设备"
+            return
+        }
+        guard !isRecording else { return }
+        videoRecorder.start()
+    }
+
+    /// 停止录制并保存 MP4 到沙盒 Documents/WebRTCRecordings。
+    func stopRecording() {
+        guard isRecording else { return }
+        videoRecorder.stop()
+    }
+
     // MARK: - 私有
 
     fileprivate func startWebRTC() {
@@ -233,6 +281,7 @@ final class ControllerViewModel: NSObject, ObservableObject {
         let client = WebRTCClient(signaling: signaling, myDeviceId: myDeviceId)
         client.delegate = self
         client.selfCodecDecoder = selfCodecDecoder
+        client.extraRenderer = videoRecorder
         webRTCClient = client
         client.createOffer(
             targetDeviceId: targetDeviceId.trimmingCharacters(in: .whitespacesAndNewlines),