feat(client/native): stats-overhaul Phase1 — 四端实时统计采集端

各原生侧把 libbox/Clash 的实时上下行/延迟经冻结的 pangolin/vpn/stats channel
生产真实帧:
- iOS/macOS 新增 StatsClient.swift(LibboxNewCommandClient,statusInterval 1s,
  uplink/downlink/总量 + urltest 延迟映射契约字段),VpnManager/VpnChannel 状态
  观察驱动 start/stop,pbxproj 登记。
- Android PangolinVpnService.kt 延迟修复。

契约字段 uploadBytes/downloadBytes/uploadSpeed/downloadSpeed/urltestResults 不改。
真机验证(连接后实时跳动)为运行时步骤,见计划 Phase1 待办。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

client/macos/Runner/VpnChannel.swift

@@ -30,7 +30,7 @@ final class VpnChannel: NSObject {
     private var statusSink: FlutterEventSink?
     private var statsSink: FlutterEventSink?
     private var statusObserver: NSObjectProtocol?
-    private var statsTimer: Timer?
+    private let statsClient = StatsClient()
     private var manager: NETunnelProviderManager?
     private var sysextDelegate: SysExtActivationDelegate?
 
@@ -142,13 +142,42 @@ final class VpnChannel: NSObject {
 
     // ── 状态 / 速率回传 ─────────────────────────────────────────────
     private func observeStatus() {
+        // StatsClient 拿到实时帧 → 推当前 statsSink。
+        statsClient.onStats = { [weak self] stats in self?.statsSink?(stats) }
         statusObserver = NotificationCenter.default.addObserver(
             forName: .NEVPNStatusDidChange, object: nil, queue: .main
         ) { [weak self] note in
-            guard let conn = note.object as? NEVPNConnection else { return }
+            guard let self, let conn = note.object as? NEVPNConnection else { return }
             let s = Self.statusString(conn.status)
             vpnLog("NEVPNStatus 变化 → \(s) (raw=\(conn.status.rawValue))")
-            self?.statusSink?(s)
+            self.statusSink?(s)
+            // 实时统计 CommandClient 跟随连接状态启停。
+            switch conn.status {
+            case .connected:
+                self.statsClient.start()
+            case .disconnected, .invalid:
+                self.statsClient.stop()
+            default:
+                break
+            }
+        }
+        // 隧道(sysext)常驻：app 重启时它可能早已 connected，此后不会再发 .connected
+        // 状态变化 → 上面的 observer 不触发、statsClient 永不 start。启动时主动探一次
+        // 现存连接：拿到 manager(让 onStatsListen 兜底也能判定)，已连则立刻拉起统计。
+        Task { await self.primeExistingConnection() }
+    }
+
+    /// 启动时若隧道已在连接，主动装配 manager 并拉起实时统计。幂等(StatsClient.start 自带去重)。
+    private func primeExistingConnection() async {
+        guard let all = try? await NETunnelProviderManager.loadAllFromPreferences(),
+              let mgr = all.first else { return }
+        await MainActor.run {
+            self.manager = mgr
+            if mgr.connection.status == .connected {
+                vpnLog("启动时检测到隧道已连接(raw=\(mgr.connection.status.rawValue))，主动启动实时统计")
+                self.statusSink?(Self.statusString(mgr.connection.status))
+                self.statsClient.start()
+            }
         }
     }
 
@@ -160,12 +189,11 @@ final class VpnChannel: NSObject {
 
     fileprivate func onStatsListen(_ sink: @escaping FlutterEventSink) {
         statsSink = sink
-        // TODO(P1): 接 libbox CommandClient 订阅实时速率;骨架先每秒推占位 0。
-        statsTimer = Timer.scheduledTimer(withTimeInterval: 1, repeats: true) { [weak self] _ in
-            self?.statsSink?(["up": 0, "down": 0, "uplinkTotal": 0, "downlinkTotal": 0])
-        }
+        // 实时速率由 StatsClient(libbox CommandClient)在隧道 connected 时产出并经
+        // onStats 回调推送;此处仅登记 sink。若已连接则补一次拉起。
+        if manager?.connection.status == .connected { statsClient.start() }
     }
-    fileprivate func onStatsCancel() { statsTimer?.invalidate(); statsTimer = nil; statsSink = nil }
+    fileprivate func onStatsCancel() { statsSink = nil }
 
     private static func statusString(_ s: NEVPNStatus) -> String {
         switch s {