fix: polish earth legend and info panel interactions

frontend/public/earth/js/legend.js

@@ -1,25 +1,21 @@
 const LEGEND_MODES = {
   cables: {
     title: "线缆图例",
-    items: [
-      { color: "#ff4444", label: "Americas II" },
-      { color: "#44ff44", label: "AU Aleutian A" },
-      { color: "#4444ff", label: "AU Aleutian B" },
-      { color: "#ffff44", label: "其他电缆" },
-    ],
   },
   satellites: {
     title: "卫星图例",
-    items: [
-      { color: "#4db8ff", label: "卫星本体" },
-      { color: "#9be7ff", label: "卫星轨迹" },
-      { color: "#7dffb3", label: "悬停高亮" },
-      { color: "#ffd166", label: "选中目标" },
-    ],
+  },
+  bgp: {
+    title: "BGP观测图例",
   },
 };
 
 let currentLegendMode = "cables";
+let legendItemsByMode = {
+  cables: [],
+  satellites: [],
+  bgp: [],
+};
 
 export function initLegend() {
   renderLegend(currentLegendMode);
@@ -27,7 +23,6 @@ export function initLegend() {
 
 export function setLegendMode(mode) {
   const nextMode = LEGEND_MODES[mode] ? mode : "cables";
-  if (nextMode === currentLegendMode) return;
   currentLegendMode = nextMode;
   renderLegend(currentLegendMode);
 }
@@ -36,12 +31,25 @@ export function getLegendMode() {
   return currentLegendMode;
 }
 
+export function refreshLegend() {
+  renderLegend(currentLegendMode);
+}
+
+export function setLegendItems(mode, items) {
+  if (!LEGEND_MODES[mode]) return;
+  legendItemsByMode[mode] = Array.isArray(items) ? items : [];
+  if (mode === currentLegendMode) {
+    renderLegend(currentLegendMode);
+  }
+}
+
 function renderLegend(mode) {
   const legend = document.getElementById("legend");
   if (!legend) return;
 
   const config = LEGEND_MODES[mode] || LEGEND_MODES.cables;
-  const itemsHtml = config.items
+  const items = legendItemsByMode[mode] || [];
+  const itemsHtml = items
     .map(
       (item) => `
         <div class="legend-item">