负载均衡重构: 子网感知选择 + 节点健康监控 + 节点注册上报API

- 新增 subnet-aware 负载策略: 根据客户端IP匹配最近/16子网节点
- 节点注册端点 (POST /api/nodes/register): 边缘节点自动注册
- 节点心跳端点 (POST /api/nodes/heartbeat): 上报CPU/RAM/带宽/连接数
- 健康汇总 (GET /api/nodes/health): 服务端汇总所有节点状态
- 配置节点新增subnet/is_origin字段
- 前端NodeManager: 实时健康状态/CPU/RAM进度条/带宽/连接数
- X-Forwarded-For/X-Real-IP透传支持客户端IP

backend/services/stream_service.py

@@ -69,12 +69,6 @@ class StreamService:
                 status=StreamStatus.live,
                 started_at=datetime.utcnow(),
             )
-            assigned = [n["id"] for n in lb.get_enabled_nodes()]
-            await self.update_stream(
-                stream.id,
-                assigned_nodes=json.dumps(assigned),
-                multicast_enabled=multicast_detector.is_available(),
-            )
             rtmp_url = media_service.get_rtmp_url(stream_key)
             transcode_mgr.start_transcode(stream_key, rtmp_url)
 
@@ -89,20 +83,22 @@ class StreamService:
             )
             transcode_mgr.stop_transcode(stream_key)
 
-    async def get_watch_urls(self, stream_key: str):
-        nodes = lb.get_enabled_nodes()
+    async def get_watch_urls(self, stream_key: str, client_ip: str | None = None):
+        best_node = lb.select_best_node(client_ip)
+        if not best_node:
+            best_node = lb.get_enabled_nodes()[0] if lb.get_enabled_nodes() else None
+
         lines = []
-        for node in nodes:
+        if best_node:
+            base_hls = f"/hls/{stream_key}"
             line_info = {
-                "node_id": node["id"],
-                "node_name": node["name"],
-                "weight": node["weight"],
+                "node_id": best_node["id"],
+                "node_name": best_node["name"],
+                "weight": best_node["weight"],
+                "type": "hls",
+                "url": f"{base_hls}/index.m3u8",
                 "qualities": [],
             }
-            base_hls = f"/hls/{stream_key}"
-            line_info["type"] = "hls"
-            line_info["url"] = f"{base_hls}/index.m3u8"
-
             for quality in settings.qualities:
                 label = quality["label"]
                 line_info["qualities"].append({