feat: parent-child transform hierarchy (UE Actor attach semantics)

- TransformComponent TRS = local (relative to parent); cached world SRT
  composed hierarchically (parent pos/rot/scale, no matrix decomposition
  shear under non-uniform parent scale)
- HierarchyComponent (parent + children, lazily attached); Scene::
  SetParent (keepWorld, cycle-safe) / GetParent / IsDescendantOf /
  SetWorldPose (world->local inverse, used by physics writeback & gizmo)
- UpdateTransforms: DFS from roots, recompose only dirty-or-dirty-
  ancestor subtrees (parents before children)
- DestroyEntity: descendants buried with parent (UE cascade)
- Serialization v2: optional Parent uuid key, two-pass relink on load
- Hierarchy panel: tree view, drag-drop reparent / drop-to-root detach,
  Create Child / Detach context menu; Inspector shows parent name
- Consumers moved to world-space reads: lights, camera pos, physics
  bodies/characters/joints/collider baking, gizmo, F-focus, AlignTo

App/editor/ViewportPanel.cpp

@@ -164,14 +164,15 @@ std::optional<entt::entity> ViewportPanel::Draw(const EditorContext &ctx,
                 if (ImGui::IsKeyPressed(ImGuiKey_F) && tr != nullptr) {
                     // F = 焦点选中实体（frame-selection）：编辑器相机
                     // 环绕 pivot 设为选中实体位置，沿视线平移对准（环
-                    // 绕距离沿用当前值，滚轮可调）
-                    ctx.editorCamera->FocusOn(tr->GetPosition());
+                    // 绕距离沿用当前值，滚轮可调）。世界位姿（层级
+                    // 实体 = 父链组合结果）
+                    ctx.editorCamera->FocusOn(tr->GetWorldPosition());
                 }
             }
 
             // ---- Gizmo 操纵杆（ImGui drawlist 叠加，无 GPU pass）----
-            // 选中实体 + 有 Transform 才出杆；矩阵分解直接写回
-            // TransformComponent（与 Inspector 同源，下一帧数值自动跟随）
+            // 选中实体 + 有 Transform 才出杆；分解 world 矩阵经
+            // SetWorldPose 写回（与 Inspector 同源，下一帧数值自动跟随）
             // PIE 运行态不出杆（编辑操作冻结）
             if (tr != nullptr && !playing) {
                 // 相机矩阵：跟随渲染源（编辑器形态 = EditorCamera，游戏
@@ -263,8 +264,8 @@ std::optional<entt::entity> ViewportPanel::Draw(const EditorContext &ctx,
                                          snapping ? snap : nullptr);
                     gizmo.dragging = ImGuizmo::IsUsing();
 
-                    // 拖拽生效：分解 world 矩阵写回 SRT（Set* 标脏 →
-                    // UpdateTransforms 重算 → 渲染下帧生效）。旋转用
+                    // 拖拽生效：分解 world 矩阵 → world SRT → 沿父链反解
+                    // local 写回（SetWorldPose；根实体 = 直写）。旋转用
                     // decompose 出的 quat 直写（UE FTransform 语义）——
                     // 不经欧拉往返，拖拽零漂移、无万向锁
                     if (ImGuizmo::IsUsing()) {
@@ -272,9 +273,8 @@ std::optional<entt::entity> ViewportPanel::Draw(const EditorContext &ctx,
                         glm::quat rot;
                         glm::vec4 persp;
                         if (glm::decompose(m, scale, rot, transl, skew, persp)) {
-                            tr->SetPosition(transl)
-                              .SetRotationQuat(rot)
-                              .SetScale(scale);
+                            ctx.scene->SetWorldPose(selected, transl, rot,
+                                                    scale);
                         }
                     }
                 }
@@ -382,7 +382,7 @@ void ViewportPanel::LogPick(const EditorContext &ctx, entt::entity e) {
                         ? "static" : "dynamic",
                     rb->boxHalfExtents.x, rb->boxHalfExtents.y,
                     rb->boxHalfExtents.z, rb->sphereRadius,
-                    tr.GetPosition().x, tr.GetPosition().y, tr.GetPosition().z);
+                    tr.GetWorldPosition().x, tr.GetWorldPosition().y, tr.GetWorldPosition().z);
     } else {
         ENGINE_INFO("[pick] '{}' (hitproxy) | (no collider)", name);
     }