feat(timeline): 支持拖拽调整时长与运镜/轨迹关键帧时间

src/editor/canvas/DirectorCanvas.grid.test.ts

@@ -1,4 +1,5 @@
 import {
+  applyExternalViewSnapshot,
   applySnapshotToControls,
   DEFAULT_DIRECTOR_VIEW_SNAPSHOT,
   getViewportGizmoHitButtonStyle,
@@ -43,6 +44,27 @@ it("flushes leftover orbit inertia before writing the reset view back", () => {
   expect(camera.position.toArray()).toEqual(DEFAULT_DIRECTOR_VIEW_SNAPSHOT.position);
 });
 
+it("writes an external view change on the spot instead of deferring it to the next render", () => {
+  // 机位视角下没有 OrbitControls：写不进去，交给切回导演视角时的副作用补写
+  expect(applyExternalViewSnapshot(null, DEFAULT_DIRECTOR_VIEW_SNAPSHOT)).toBe(false);
+
+  const dampingStateDuringUpdate: boolean[] = [];
+  const controls = {
+    enableDamping: true,
+    target: new Vector3(9, 9, 9),
+    object: new PerspectiveCamera(),
+    update: () => dampingStateDuringUpdate.push(controls.enableDamping),
+  };
+
+  expect(applyExternalViewSnapshot(controls, DEFAULT_DIRECTOR_VIEW_SNAPSHOT)).toBe(true);
+
+  // 当场就把残余惯性结算掉并落到目标视角（惯性滑行中点重置视角不会再被推走）
+  expect(dampingStateDuringUpdate).toEqual([false, false]);
+  expect(controls.target.toArray()).toEqual(DEFAULT_DIRECTOR_VIEW_SNAPSHOT.target);
+  expect(controls.object.position.toArray()).toEqual(DEFAULT_DIRECTOR_VIEW_SNAPSHOT.position);
+  expect(controls.enableDamping).toBe(true);
+});
+
 it("keeps the viewport grid visible when a panorama background is active", () => {
   expect(shouldRenderViewportGrid(true, false)).toBe(true);
 });