fix(renderer): mesh collider source positions in render space for skinned meshes

Skinned meshes keep vertices in raw mesh space (bakeTransform=false);
rendering transforms them via bind palette (global(bone) x invBind, folds
FBX unit scale). Physics MeshShape/ConvexHull and the mesh bounding sphere
consumed the raw positions directly -> M1911 hull measured ~10x the visual
size. ParseFromDisk now bakes bind-palette-skinned positions per vertex
(same formula as the skinning shader) into ParsedMesh::cpuPositions; Mesh
uses them for m_CpuPositions and bounds. GPU vertex data and rendering are
untouched.

Engine/src/Renderer/Mesh.cpp

@@ -25,7 +25,8 @@ namespace Engine
     Mesh::Mesh(Device& device, MemoryAllocator& allocator,
                const std::vector<Vertex>& vertices,
                const std::vector<std::vector<u32>>& lods,
-               Material* material)
+               Material* material,
+               const std::vector<glm::vec3>* cpuPositions)
         : m_Material(material)
         , m_Slot(s_nextMeshSlot.fetch_add(1, std::memory_order_relaxed))
     {
@@ -35,11 +36,19 @@ namespace Engine
             return;
         }
 
+        // 位置取数：蒙皮 mesh 用绑定姿态渲染空间副本（与视觉同源），
+        // 否则用原始顶点位置
+        const bool useBind = cpuPositions != nullptr &&
+                             cpuPositions->size() == vertices.size();
+        auto posAt = [&](size_t i) -> const glm::vec3& {
+            return useBind ? (*cpuPositions)[i] : vertices[i].position;
+        };
+
         // CPU 位置副本：物理 MeshShape/ConvexHull 数据源（GPU 上传后
         // 完整 Vertex 不再保留，见 Mesh.h）
         m_CpuPositions.reserve(vertices.size());
-        for (const auto& v : vertices) {
-            m_CpuPositions.push_back(v.position);
+        for (size_t i = 0; i < vertices.size(); ++i) {
+            m_CpuPositions.push_back(posAt(i));
         }
         m_CpuIndices = lods[0];
 
@@ -78,18 +87,19 @@ namespace Engine
         }
 
         // 局部空间包围球：顶点包围盒 → 中心 + 最大半径（视锥剔除用）
+        // 蒙皮 mesh 用绑定姿态副本（原始空间包围球大一个数量级 = 剔除/拾取失真）
         {
             glm::vec3 mn(std::numeric_limits<f32>::max());
             glm::vec3 mx(std::numeric_limits<f32>::lowest());
-            for (const auto& v : vertices) {
-                mn = glm::min(mn, v.position);
-                mx = glm::max(mx, v.position);
+            for (size_t i = 0; i < vertices.size(); ++i) {
+                mn = glm::min(mn, posAt(i));
+                mx = glm::max(mx, posAt(i));
             }
             m_Bounds.center = (mn + mx) * 0.5f;
             m_Bounds.radius = 0.0f;
-            for (const auto& v : vertices) {
+            for (size_t i = 0; i < vertices.size(); ++i) {
                 m_Bounds.radius = glm::max(m_Bounds.radius,
-                                           glm::length(v.position - m_Bounds.center));
+                                           glm::length(posAt(i) - m_Bounds.center));
             }
         }