9978ac3e01
后端 city_realtime_stream.py:循环缓冲区(deque maxlen=1440),best_temp() METAR优先。路由 /api/city/{name}/realtime-stream 返回 {points, thresholds}。前端 RealtimeScrollChart:每30秒轮询,一条温度线+多条阈值横线,横轴随时间推进。