便签锚点贴到地形表面，修复放大旋转时的漂移

src/scene/CesiumGlobe.js

@@ -299,6 +299,7 @@ export class CesiumGlobe {
     viewer.clock.shouldAnimate = false;
 
     this._buildMarkers();
+    this._clampMarkersToTerrain();
     this._setupPick();
     this._setupRightRestore();
     this._loadBoundaries();
@@ -327,6 +328,8 @@ export class CesiumGlobe {
       const noteNormal = makeStickyNote(entry.name, 16, false);
       const noteSelected = makeStickyNote(entry.name, 16, true);
       this.markers.push({
+        lng: entry.lng,
+        lat: entry.lat,
         position,
         r2: Cesium.Cartesian3.magnitudeSquared(position),
         noteNormal,
@@ -337,6 +340,29 @@ export class CesiumGlobe {
     this._initMarkerLayer();
   }
 
+  // 把便签锚点贴到地形表面（否则在椭球面高度 0 上，放大旋转时会飘）
+  async _clampMarkersToTerrain() {
+    const scene = this.viewer.scene;
+    if (!scene || !scene.globe) return;
+    const cartos = this.markers.map((m) =>
+      Cesium.Cartographic.fromDegrees(m.lng, m.lat),
+    );
+    try {
+      await scene.sampleHeightMostDetailed(cartos);
+    } catch (err) {
+      console.warn('[CesiumGlobe] 地形高度采样失败，便签保持椭球面高度：', err);
+      return;
+    }
+    for (let i = 0; i < this.markers.length; i++) {
+      const h = cartos[i] && cartos[i].height;
+      if (h != null && isFinite(h)) {
+        const m = this.markers[i];
+        m.position = Cesium.Cartesian3.fromDegrees(m.lng, m.lat, h);
+        m.r2 = Cesium.Cartesian3.magnitudeSquared(m.position);
+      }
+    }
+  }
+
   // 便签用 DOM 覆盖层渲染：始终在城市/国家名上层，且缩放到最近也不会漂移
   _initMarkerLayer() {
     const container = document.getElementById('cesium-container');