feat: update userapp views

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

qy_lty/userapp/views.py

@@ -116,7 +116,8 @@ class MacAddressLoginView(APIView):
             device = Device.objects.get(mac_address=mac_address)
 
             # 检查设备是否已绑定给用户
-            user_device = UserDevice.objects.filter(device=device).first()
+            # 按绑定时间倒序取最新绑定者作为设备归属人——"后绑的挤掉先绑的"
+            user_device = UserDevice.objects.filter(device=device).order_by('-bound_at').first()
             if not user_device:
                 logger.warning(f"Device not bound to any user: {mac_address}")
                 # 返回特定 code=4010，让设备端可以识别"未绑定"状态