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/Vulkan/DescriptorManager.cpp

@@ -11,24 +11,32 @@ namespace Engine
     DescriptorManager::DescriptorManager(Device& device)
         : m_Device(device)
     {
-        std::array<vk::DescriptorPoolSize, 3> poolSizes = {
-            vk::DescriptorPoolSize(vk::DescriptorType::eUniformBuffer, kMaxSets),
-            vk::DescriptorPoolSize(vk::DescriptorType::eCombinedImageSampler, kMaxSets),
-            vk::DescriptorPoolSize(vk::DescriptorType::eStorageBuffer, kMaxSets),
-        };
-
-        vk::DescriptorPoolCreateInfo poolInfo;
-        poolInfo.setMaxSets(kMaxSets)
-                .setPoolSizes(poolSizes)
-                .setFlags(vk::DescriptorPoolCreateFlagBits::eFreeDescriptorSet);
-
-        m_Pool = m_Device.GetDevice().createDescriptorPool(poolInfo);
-        ENGINE_INFO("DescriptorManager created");
+        m_Pools.push_back(CreateChunk());
+        ENGINE_INFO("DescriptorManager created (growable, chunk = {} sets)",
+                    kChunkSets);
     }
 
     DescriptorManager::~DescriptorManager()
     {
-        m_Device.GetDevice().destroyDescriptorPool(m_Pool);
+        for (auto pool : m_Pools) {
+            m_Device.GetDevice().destroyDescriptorPool(pool);
+        }
+    }
+
+    vk::DescriptorPool DescriptorManager::CreateChunk()
+    {
+        std::array<vk::DescriptorPoolSize, 3> poolSizes = {
+            vk::DescriptorPoolSize(vk::DescriptorType::eUniformBuffer, kChunkSets),
+            vk::DescriptorPoolSize(vk::DescriptorType::eCombinedImageSampler, kChunkSets),
+            vk::DescriptorPoolSize(vk::DescriptorType::eStorageBuffer, kChunkSets),
+        };
+
+        vk::DescriptorPoolCreateInfo poolInfo;
+        poolInfo.setMaxSets(kChunkSets)
+                .setPoolSizes(poolSizes)
+                .setFlags(vk::DescriptorPoolCreateFlagBits::eFreeDescriptorSet);
+
+        return m_Device.GetDevice().createDescriptorPool(poolInfo);
     }
 
     vk::DescriptorSetLayout DescriptorManager::CreateLayout(const std::vector<DescriptorBinding>& bindings)
@@ -52,12 +60,24 @@ namespace Engine
 
     vk::DescriptorSet DescriptorManager::AllocateDescriptorSet(vk::DescriptorSetLayout layout)
     {
-        vk::DescriptorSetAllocateInfo allocInfo;
-        allocInfo.setDescriptorPool(m_Pool)
-                 .setSetLayouts(layout);
-
-        auto sets = m_Device.GetDevice().allocateDescriptorSets(allocInfo);
-        return sets[0];
+        // 从最新块分配；耗尽（OutOfPool/Fragmented）则追加一块重试
+        for (;;) {
+            try {
+                vk::DescriptorSetAllocateInfo allocInfo;
+                allocInfo.setDescriptorPool(m_Pools.back())
+                         .setSetLayouts(layout);
+                auto sets = m_Device.GetDevice().allocateDescriptorSets(allocInfo);
+                return sets[0];
+            } catch (const vk::OutOfPoolMemoryError&) {
+                m_Pools.push_back(CreateChunk());
+                ENGINE_INFO("DescriptorManager: pool chunk grown -> {} chunks",
+                            m_Pools.size());
+            } catch (const vk::FragmentedPoolError&) {
+                m_Pools.push_back(CreateChunk());
+                ENGINE_INFO("DescriptorManager: pool fragmented, new chunk -> {}",
+                            m_Pools.size());
+            }
+        }
     }
 
     void DescriptorManager::UpdateUniformBuffer(vk::DescriptorSet set, u32 binding,