性能优化：精简便签每帧计算、地理视图跳过 Three.js 每帧逻辑

src/core/App.js

@@ -252,8 +252,11 @@ export class App {
     window.addEventListener('resize', () => this._onResize());
 
     window.addEventListener('keydown', (e) => {
-      if (e.key === 'ArrowRight') this._step(1);
-      else if (e.key === 'ArrowLeft') this._step(-1);
+      if (e.key === 'ArrowRight' || e.key === 'ArrowLeft') {
+        const dir = e.key === 'ArrowRight' ? 1 : -1;
+        if (this.view === 'timeline') this._stepTimeline(dir);
+        else this._step(dir);
+      }
       else if (e.key === '1') this.switchView('binder');
       else if (e.key === '2') this.switchView('timeline');
       else if (e.key === '3') this.switchView('globe');
@@ -357,6 +360,15 @@ export class App {
     else this.binder.flipBackward();
   }
 
+  // 时间轴：左右键选择上一张/下一张，动画与点击一致（居中 + 翻面）
+  _stepTimeline(dir) {
+    const next = clamp(this.selected + dir, 0, ENTRIES.length - 1);
+    if (next === this.selected) return;
+    this._select(next, { syncBinder: true });
+    this._centerTimeline(next);
+    this.timeline.flip(next);
+  }
+
   _select(index, { syncBinder = false } = {}) {
     this.selected = clamp(index, 0, ENTRIES.length - 1);
     const entry = ENTRIES[this.selected];
@@ -492,6 +504,7 @@ export class App {
 
   _animate() {
     requestAnimationFrame(this._animate);
+    if (this.view === 'globe') return; // 地理视图由 Cesium 渲染，跳过 Three.js 每帧逻辑
     const dt = Math.min(this.clock.getDelta(), 0.05);
 
     // 是否有进行中的动画（决定本帧是否需要重绘）