🔔 飞行侠实现：实例注册 + Webhook 推送

新功能:
- instances 应用：OpenClaw 实例管理
- Instance 模型：实例注册，Agent 列表，Webhook URL
- MeetingInstanceMap：会议 - 实例映射
- Webhook 推送：消息发送时自动通知相关实例

API 端点:
- POST /api/v1/instances/register/ - 实例注册
- POST /api/v1/instances/join-meeting/ - 加入会议
- GET  /api/v1/instances/ - 实例列表
- POST /api/v1/instances/webhook-test/ - Webhook 测试

集成:
- send_message API 自动触发 Webhook 推送
- 支持广播和定向推送

测试:
- test_webhook.py: 完整测试流程

使用场景:
1. 每台 OpenClaw 机器注册实例
2. Agent 加入会议时关联实例
3. 消息发送时推送到对应机器
4. 本机 OpenClaw 收到通知，触发 Agent 响应

backend/instances/webhook.py

@@ -0,0 +1,147 @@
+#!/usr/bin/env python3
+"""
+Webhook 推送工具
+"""
+
+import requests
+import logging
+from typing import Dict, List, Optional
+from .models import Instance, MeetingInstanceMap
+
+logger = logging.getLogger(__name__)
+
+
+def push_message_to_instances(meeting_id: str, message: Dict, target_agent_ids: Optional[List[str]] = None):
+    """
+    推送消息到相关实例
+    
+    Args:
+        meeting_id: 会议 ID
+        message: 消息数据（字典）
+        target_agent_ids: 目标 Agent ID 列表（None 表示广播给所有）
+    """
+    # 找到参与该会议的实例
+    maps = MeetingInstanceMap.objects.filter(
+        meeting_id=meeting_id,
+        left_at__isnull=True,
+        instance__is_active=True,
+        instance__webhook_enabled=True
+    ).select_related('instance')
+    
+    for mapping in maps:
+        instance = mapping.instance
+        
+        # 确定要推送的 Agent
+        if target_agent_ids:
+            # 只推送给指定的 Agent
+            agents_to_notify = [aid for aid in mapping.agent_ids if aid in target_agent_ids]
+        else:
+            # 广播给所有
+            agents_to_notify = mapping.agent_ids
+        
+        if not agents_to_notify:
+            continue
+        
+        # 构建推送数据
+        payload = {
+            'event': 'new_message',
+            'meeting_id': str(meeting_id),
+            'message': message,
+            'target_agents': agents_to_notify,
+            'timestamp': message.get('created_at', '')
+        }
+        
+        # 发送 webhook
+        try:
+            response = requests.post(
+                instance.webhook_url,
+                json=payload,
+                headers={'Content-Type': 'application/json'},
+                timeout=5
+            )
+            
+            if response.status_code == 200:
+                logger.info(f"✅ Webhook 推送成功：{instance.instance_id} -> {agents_to_notify}")
+            else:
+                logger.warning(f"⚠️ Webhook 推送失败：{instance.instance_id}, status={response.status_code}")
+        except Exception as e:
+            logger.error(f"❌ Webhook 推送异常：{instance.instance_id}, error={e}")
+
+
+def register_instance(instance_id: str, instance_name: str, agent_ids: List[str], webhook_url: str) -> Instance:
+    """
+    注册或更新实例
+    
+    Args:
+        instance_id: 实例 ID
+        instance_name: 实例名称
+        agent_ids: Agent ID 列表
+        webhook_url: Webhook URL
+    
+    Returns:
+        Instance: 实例对象
+    """
+    instance, created = Instance.objects.update_or_create(
+        instance_id=instance_id,
+        defaults={
+            'instance_name': instance_name,
+            'agent_ids': agent_ids,
+            'webhook_url': webhook_url,
+            'webhook_enabled': True,
+            'is_active': True
+        }
+    )
+    
+    if created:
+        logger.info(f"✅ 新实例注册：{instance_id} ({instance_name})")
+    else:
+        logger.info(f"🔄 实例更新：{instance_id}")
+    
+    return instance
+
+
+def join_meeting(instance_id: str, meeting_id: str, agent_ids: List[str]):
+    """
+    实例加入会议
+    
+    Args:
+        instance_id: 实例 ID
+        meeting_id: 会议 ID
+        agent_ids: 参与的 Agent ID 列表
+    """
+    try:
+        instance = Instance.objects.get(instance_id=instance_id)
+        
+        MeetingInstanceMap.objects.update_or_create(
+            meeting_id=meeting_id,
+            instance=instance,
+            defaults={'agent_ids': agent_ids, 'left_at': None}
+        )
+        
+        logger.info(f"✅ 实例 {instance_id} 加入会议 {meeting_id}, Agents: {agent_ids}")
+    except Instance.DoesNotExist:
+        logger.error(f"❌ 实例不存在：{instance_id}")
+        raise
+
+
+def leave_meeting(instance_id: str, meeting_id: str):
+    """
+    实例离开会议
+    
+    Args:
+        instance_id: 实例 ID
+        meeting_id: 会议 ID
+    """
+    try:
+        instance = Instance.objects.get(instance_id=instance_id)
+        mapping = MeetingInstanceMap.objects.get(meeting_id=meeting_id, instance=instance)
+        mapping.left_at = timezone.now()
+        mapping.save()
+        
+        logger.info(f"✅ 实例 {instance_id} 离开会议 {meeting_id}")
+    except Exception as e:
+        logger.warning(f"⚠️ 离开会议失败：{e}")
+
+
+# 导入 timezone
+from django.utils import timezone