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

Engine/src/Renderer/SceneRenderer.cpp

@@ -354,7 +354,7 @@ namespace Engine
                                                                    : 2.0f);
 
             if (light.type == LightComponent::Type::Point) {
-                dst.position = glm::vec4(t.GetPosition(), 1.0f);
+                dst.position = glm::vec4(t.GetWorldPosition(), 1.0f);
                 dst.direction = glm::vec4(0.0f);
             } else {
                 glm::vec3 dir = glm::length(light.direction) > 0.0f
@@ -391,7 +391,7 @@ namespace Engine
             shadowDir = glm::vec3(collected[0].direction);
         }
         ComputeCascades(shadowDir);
-        ubo.cameraPos = glm::vec4(camTransform->GetPosition(), 1.0f);
+        ubo.cameraPos = glm::vec4(camTransform->GetWorldPosition(), 1.0f);
 
         // ---- 2.5 骨骼动画推进 + 姿态采样（与可见性无关：播放头恒走，
         //      否则被剔除的实体回屏时动画跳变）----
@@ -579,7 +579,7 @@ namespace Engine
                     // LOD 选级：屏占比近似 = radius/距离（主视图按实例距离；
                     // 阈值 10/20 倍半径，可调）。开关关闭 = 恒 LOD0
                     const f32 dist =
-                        glm::length(worldCenter - camTransform->GetPosition());
+                        glm::length(worldCenter - camTransform->GetWorldPosition());
                     u32 mainLod = 0;
                     if (m_LodEnabled) {
                         if (dist >= worldRadius * 20.0f) {