fix: 地图拖动/缩放时流量边实时跟随

- moveend事件清空边坐标缓存+立即重绘
- 不每帧重复绑定handler

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

simple_analysis/templates/simple_analysis/simple_analysis.html

@@ -2672,6 +2672,7 @@ function loadTrafficData() {
         document.getElementById('saTrafficSlider').value = 0;
         document.getElementById('saTrafficInfo').textContent =
             (d.windows||[]).length + ' 窗口 · ' + Object.keys(d.nodes_coords||{}).length + ' 节点 · 跨度' + ((maxTs-minTs)/60).toFixed(0) + 'min';
+        SA.map.off('moveend.flowCache').on('moveend.flowCache', () => { _trafficEdgeCache = {}; });
         document.getElementById('saTrafficTime').textContent = tsToBJ(_trafficCurrentTime);
         trafficStart();
     })
@@ -2847,8 +2848,6 @@ function renderTrafficCrossfade() {
         }
     });
 
-    SA.map.off('moveend.flowCache').on('moveend.flowCache', () => { _trafficEdgeCache = {}; });
-
     if (SA.pointLayer && !SA._clusterFocus) {
         SA.pointLayer.getLayers().forEach(l => {
             if (!l.setStyle) return;