camera: UE Scene-view semantics — RMB fly, MMB focus-orbit, wheel dolly, F focus

Key conflict fix (UE semantics): while RMB is held the keyboard belongs
to the camera, so WASD no longer collides with the gizmo W/E/R tool
hotkeys. Editor mode gates fly movement behind RMB; game mode keeps
always-on WASD. Viewport tool hotkeys (W/E/R/T/F) are suppressed while
RMB is held.

Focus orbit (pivot): MMB drag rotates the camera around a pivot keeping
distance; first orbit picks a pivot 5m ahead on the view ray. Shift+MMB
pans in screen plane (camera and pivot move together). Mouse wheel
dollies toward/away from the pivot with exponential steps (no pivot:
move along view ray). F focuses the selected entity (frame-selection):
pivot set to its position, camera slides along the view ray; orbit
distance persists.

Window gains a polled scroll-delta channel (ConsumeScrollDelta) that
respects ImGui mouse capture; Camera::Update mutates orbit state (no
longer const).

App/main.cpp

@@ -201,12 +201,15 @@ namespace
 
         void OnUpdate(const FrameTime& frameTime) override
         {
-            // 相机（WASD/Space/Shift 移动；位姿读写实体 Transform）。
-            // 编辑器相机走真实轨：暂停（timeScale=0）时仍可飞行观察
+            // 相机（RMB 飞行 / MMB 焦点环绕 / 滚轮推拉；位姿读写实体
+            // Transform）。编辑器相机走真实轨：暂停（timeScale=0）时仍
+            // 可飞行观察。编辑器模式移动键需 RMB 按住（UE 语义：飞行时
+            // 键盘归相机，W/E/R 归 Gizmo）
             m_Camera.GetComponent<CameraComponent>()
                     .camera.Update(GetWindow(),
                                    m_Camera.GetComponent<TransformComponent>(),
-                                   frameTime.UnscaledDt());
+                                   frameTime.UnscaledDt(),
+                                   GetRenderer().GetDisplayMode() == kDisplayViewport);
 
             // 旋转动画：编辑 Transform 分量后 Compose 重算 world。
             // 动画时钟 = Time::Elapsed()（scaled 累计，暂停自动冻结——