feat(earth): add cable-landing point relation via city_id

Backend:
- Fix arcgis_landing collector to extract city_id
- Fix arcgis_relation collector to extract city_id
- Fix convert_landing_point_to_geojson to use city_id mapping

Frontend:
- Update landing point cableNames to use array
- Add applyLandingPointVisualState for cable lock highlight
- Dim all landing points when satellite is locked

frontend/public/earth/js/cables.js

@@ -286,7 +286,7 @@ export async function loadLandingPoints(scene, earthObj) {
       sphere.userData = {
         type: 'landingPoint',
         name: properties.name || '未知登陆站',
-        cableName: properties.cable_system || '未知系统',
+        cableNames: properties.cable_names || [],
         country: properties.country || '未知国家',
         status: properties.status || 'Unknown'
       };
@@ -362,3 +362,47 @@ export function getCableStateInfo() {
   });
   return states;
 }
+
+export function getLandingPointsByCableName(cableName) {
+  return landingPoints.filter(lp => lp.userData.cableNames?.includes(cableName));
+}
+
+export function getAllLandingPoints() {
+  return landingPoints;
+}
+
+export function applyLandingPointVisualState(lockedCableName, dimAll = false) {
+  const pulse = (Math.sin(Date.now() * 0.003) + 1) * 0.5;
+  const brightness = 0.3;
+  
+  landingPoints.forEach(lp => {
+    const isRelated = !dimAll && lp.userData.cableNames?.includes(lockedCableName);
+    
+    if (isRelated) {
+      lp.material.color.setHex(0xffaa00);
+      lp.material.emissive.setHex(0x442200);
+      lp.material.emissiveIntensity = 0.5 + pulse * 0.5;
+      lp.material.opacity = 0.8 + pulse * 0.2;
+      lp.scale.setScalar(1.2 + pulse * 0.3);
+    } else {
+      const r = 255 * brightness;
+      const g = 170 * brightness;
+      const b = 0 * brightness;
+      lp.material.color.setRGB(r / 255, g / 255, b / 255);
+      lp.material.emissive.setHex(0x000000);
+      lp.material.emissiveIntensity = 0;
+      lp.material.opacity = 0.3;
+      lp.scale.setScalar(1.0);
+    }
+  });
+}
+
+export function resetLandingPointVisualState() {
+  landingPoints.forEach(lp => {
+    lp.material.color.setHex(0xffaa00);
+    lp.material.emissive.setHex(0x442200);
+    lp.material.emissiveIntensity = 0.5;
+    lp.material.opacity = 1.0;
+    lp.scale.setScalar(1.0);
+  });
+}