fix: 视锥剔除平面归一化（透视因数误剔）+ 材质去重 + 描述符池可增长

- Frustum::FromMatrix 平面归一化：Gribb-Hartmann 提取的 left/right/
  bottom/top 法线模长含 1/tan(fov/2) 因子（>1），未归一化时包围球
  距离测试被放大，视锥边缘物体被误剔（SunTemple 全场景可见）——
  修正注释：必须传 [0,1] 重映射矩阵
- 材质去重：Model 新增 MaterialCache（按贴图路径共享 Material），
  Mesh 改持 Material* 非拥有指针。1056 mesh 渲染只需 48 个描述符集
  （对齐 UE/Unity 材质实例化思路，大场景第一道闸门）
- DescriptorManager 池改可增长分块（chunk=4096，OutOfPool/Fragmented
  自动续块）：材质集数量不可预估（1G 资产可能上万），固定上限迟早爆

Engine/src/Renderer/Mesh.cpp

@@ -18,8 +18,8 @@ namespace Engine
     Mesh::Mesh(Device& device, MemoryAllocator& allocator,
                const std::vector<Vertex>& vertices,
                const std::vector<u32>& indices,
-               Scope<Material> material)
-        : m_Material(std::move(material))
+               Material* material)
+        : m_Material(material)
     {
         if (vertices.empty() || indices.empty())
         {

Engine/src/Renderer/Model.cpp

@@ -59,14 +59,12 @@ Model::Model(Device& device, MemoryAllocator& allocator,
     };
     const std::vector<u32> indices = {0, 1, 2, 0, 2, 3};
 
-    auto mat = CreateScope<Material>(
-        m_Device, m_DescriptorManager, m_TextureLayout, tex.get());
+    // 贴图/材质生命周期随模型（缓存持有）
+    m_DefaultTexture = std::move(tex);
+    Material* mat = GetOrCreateMaterial("");   // 兜底材质
 
     m_Meshes.push_back(CreateScope<Mesh>(
-        m_Device, m_Allocator, vertices, indices, std::move(mat)));
-
-    // 贴图生命周期随模型
-    m_DefaultTexture = std::move(tex);
+        m_Device, m_Allocator, vertices, indices, mat));
 }
 
 Scope<Model> Model::CreatePlane(Device& device, MemoryAllocator& allocator,
@@ -134,6 +132,34 @@ Texture* Model::GetOrLoadTexture(const std::string& rawPath)
     return ptr;
 }
 
+Material* Model::GetOrCreateMaterial(const std::string& rawPath)
+{
+    // 路径归一化 + 空路径/缺文件统一折到兜底材质（缓存键 ""）
+    std::string path = rawPath;
+    std::replace(path.begin(), path.end(), '\\', '/');
+
+    if (path.empty() || !std::filesystem::exists(path)) {
+        if (!rawPath.empty()) {
+            ENGINE_WARN("Texture not found, using default: {}", path);
+        }
+        path.clear();
+    }
+
+    if (auto it = m_MaterialCache.find(path); it != m_MaterialCache.end()) {
+        return it->second.get();
+    }
+
+    Texture* tex = path.empty()
+        ? m_DefaultTexture.get()
+        : GetOrLoadTexture(path);
+
+    auto mat = CreateScope<Material>(
+        m_Device, m_DescriptorManager, m_TextureLayout, tex);
+    Material* ptr = mat.get();
+    m_MaterialCache.emplace(path, std::move(mat));
+    return ptr;
+}
+
 Scope<Mesh> Model::ProcessMesh(aiMesh* mesh, const aiScene* scene)
 {
     std::vector<Vertex> vertices;
@@ -189,16 +215,11 @@ Scope<Mesh> Model::ProcessMesh(aiMesh* mesh, const aiScene* scene)
         }
     }
 
-    // 从缓存拿，没有才加载
-    Texture* tex = texturePath.empty()
-        ? m_DefaultTexture.get()
-        : GetOrLoadTexture(texturePath);
-
-    auto mat = CreateScope<Material>(
-        m_Device, m_DescriptorManager, m_TextureLayout, tex);
+    // 材质缓存：同贴图 → 同一 Material（一个描述符集），mesh 数 ≠ 集数
+    Material* mat = GetOrCreateMaterial(texturePath);
 
     return CreateScope<Mesh>(
-        m_Device, m_Allocator, vertices, indices, std::move(mat));
+        m_Device, m_Allocator, vertices, indices, mat);
 }
 
 } // namespace Engine