fix: polish earth toolbar controls and loading copy

frontend/public/earth/js/main.js

@@ -9,6 +9,7 @@ import {
   updateZoomDisplay,
   updateEarthStats,
   setLoading,
+  setLoadingMessage,
   showTooltip,
   hideTooltip,
   showError,
@@ -392,6 +393,12 @@ async function loadData(showWhiteSphere = false) {
   const loadToken = ++currentLoadToken;
   isDataLoading = true;
   hideError();
+  setLoadingMessage(
+    showWhiteSphere ? "正在刷新全球态势数据..." : "正在初始化全球态势数据...",
+    showWhiteSphere
+      ? "重新同步卫星、海底光缆与登陆点数据"
+      : "同步卫星、海底光缆与登陆点数据",
+  );
   setLoading(true);
   clearLockedObject();
   hideInfoCard();
@@ -761,11 +768,19 @@ function animate() {
 
   const earth = getEarth();
   const deltaTime = clock.getDelta() * 1000;
+  const hasInertia =
+    Math.abs(inertialVelocity.x) > INERTIA_MIN_VELOCITY ||
+    Math.abs(inertialVelocity.y) > INERTIA_MIN_VELOCITY;
 
   if (getAutoRotate() && earth) {
     earth.rotation.y += CONFIG.rotationSpeed * (deltaTime / 16);
-    targetRotation.y = earth.rotation.y;
-    targetRotation.x = earth.rotation.x;
+
+    // Keep the drag target aligned with autorotation only when the user is not
+    // actively dragging and there is no residual inertial motion to preserve.
+    if (!isDragging && !hasInertia) {
+      targetRotation.y = earth.rotation.y;
+      targetRotation.x = earth.rotation.x;
+    }
   }
 
   if (earth) {