功能：添加心跳守护线程，每30秒向 WVP 上报设备状态

- 新增 _start_heartbeat() 守护线程
- 每30秒 POST 到 WVP /api/ai/device/heartbeat
- 上报 uptime、帧数、告警数、活跃流数、配置版本
- 使用 stop_event.wait(30) 优雅退出

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

main.py

@@ -54,6 +54,7 @@ class EdgeInferenceService:
         self._debug_reload_thread: Optional[threading.Thread] = None
         self._debug_http_server = None
         self._debug_http_thread: Optional[threading.Thread] = None
+        self._heartbeat_thread: Optional[threading.Thread] = None
         
         self._processing_threads: Dict[str, threading.Thread] = {}
         self._stop_event = threading.Event()
@@ -284,6 +285,54 @@ class EdgeInferenceService:
         )
         self._debug_http_thread.start()
 
+    def _start_heartbeat(self):
+        """启动心跳守护线程，每 30 秒向 WVP 上报设备状态"""
+        def worker():
+            import requests
+            base_url = self._settings.alarm_upload.cloud_api_url.rstrip("/")
+            url = f"{base_url}/api/ai/device/heartbeat"
+            device_id = self._settings.mqtt.device_id
+
+            self._logger.info(f"[心跳] 守护线程已启动, 目标: {url}, device_id={device_id}")
+
+            while not self._stop_event.is_set():
+                try:
+                    start_time = self._performance_stats.get("start_time")
+                    uptime = (datetime.now() - start_time).total_seconds() if start_time else 0
+                    stream_count = len(self._stream_manager._streams) if self._stream_manager else 0
+                    config_version = self._config_manager.config_version if self._config_manager else None
+
+                    payload = {
+                        "device_id": device_id,
+                        "status": {
+                            "uptime_seconds": int(uptime),
+                            "frames_processed": self._performance_stats.get("total_frames_processed", 0),
+                            "alerts_generated": self._performance_stats.get("total_alerts_generated", 0),
+                            "stream_count": stream_count,
+                            "config_version": config_version,
+                            "stream_stats": {
+                                "active_streams": stream_count,
+                            },
+                        },
+                    }
+
+                    resp = requests.post(url, json=payload, timeout=10)
+                    if resp.status_code == 200:
+                        self._logger.debug(f"[心跳] 上报成功: uptime={int(uptime)}s, streams={stream_count}")
+                    else:
+                        self._logger.warning(f"[心跳] 上报失败: HTTP {resp.status_code}")
+                except Exception as e:
+                    self._logger.warning(f"[心跳] 上报异常: {e}")
+
+                self._stop_event.wait(30)
+
+        self._heartbeat_thread = threading.Thread(
+            target=worker,
+            name="HeartbeatWorker",
+            daemon=True,
+        )
+        self._heartbeat_thread.start()
+
     def initialize(self):
         """初始化所有组件"""
         self._logger.info("=" * 50)
@@ -301,6 +350,7 @@ class EdgeInferenceService:
         self._init_screenshot_handler()
         self._start_debug_reload_watcher()
         self._start_debug_http_server()
+        self._start_heartbeat()
         
         self._performance_stats["start_time"] = datetime.now()