refactor: reorganize Resources module into Core/Asset, Core/IO and Resources subdirectories

- Split core resource architecture into Core/Asset/ (IResource, ResourceManager, ResourceCache, etc.)
- Moved IO layer into Core/IO/ (IResourceLoader, ResourceFileSystem, etc.)
- Reorganized concrete resource types into Resources/{Texture,Mesh,Material,Shader,AudioClip}/
- Updated all include paths from relative to <XCEngine/...> format
- Fixed circular dependency in Material.h (removed unnecessary ResourceManager.h include)
- Fixed malformed include syntax in ResourceManager.h and AsyncLoader.h
- Fixed glad.h path issues in CMakeLists.txt

engine/src/Resources/Material/MaterialLoader.cpp

@@ -0,0 +1,73 @@
+#include "Resources/MaterialLoader.h"
+#include "Resources/ResourceManager.h"
+#include "Resources/ResourceTypes.h"
+
+namespace XCEngine {
+namespace Resources {
+
+MaterialLoader::MaterialLoader() = default;
+
+MaterialLoader::~MaterialLoader() = default;
+
+Containers::Array<Containers::String> MaterialLoader::GetSupportedExtensions() const {
+    Containers::Array<Containers::String> extensions;
+    extensions.PushBack("mat");
+    extensions.PushBack("material");
+    extensions.PushBack("json");
+    return extensions;
+}
+
+bool MaterialLoader::CanLoad(const Containers::String& path) const {
+    Containers::String ext = GetExtension(path);
+    return ext == "mat" || ext == "material" || ext == "json";
+}
+
+LoadResult MaterialLoader::Load(const Containers::String& path, const ImportSettings* settings) {
+    Containers::Array<Core::uint8> data = ReadFileData(path);
+    if (data.Empty()) {
+        return LoadResult("Failed to read material file: " + path);
+    }
+    
+    Material* material = new Material();
+    material->m_path = path;
+    material->m_name = path;
+    material->m_guid = ResourceGUID::Generate(path);
+    
+    Containers::String jsonStr;
+    jsonStr.Reserve(data.Size());
+    for (size_t i = 0; i < data.Size(); ++i) {
+        jsonStr += static_cast<char>(data[i]);
+    }
+    
+    size_t shaderPos = jsonStr.Find("\"shader\"");
+    if (shaderPos != Containers::String::npos) {
+        size_t colonPos = jsonStr.Find(":", shaderPos);
+        if (colonPos != Containers::String::npos) {
+            size_t quoteStart = jsonStr.Find("\"", colonPos);
+            size_t quoteEnd = jsonStr.Find("\"", quoteStart + 1);
+            if (quoteStart != Containers::String::npos && quoteEnd != Containers::String::npos) {
+                Containers::String shaderPath = jsonStr.Substring(quoteStart + 1, quoteEnd - quoteStart - 1);
+                auto shaderHandle = ResourceManager::Get().Load<Shader>(shaderPath);
+                if (shaderHandle.IsValid()) {
+                    material->SetShader(shaderHandle);
+                }
+            }
+        }
+    }
+    
+    material->m_isValid = true;
+    material->m_memorySize = sizeof(Material) + material->m_name.Length() + material->m_path.Length();
+    
+    return LoadResult(material);
+}
+
+ImportSettings* MaterialLoader::GetDefaultSettings() const {
+    return nullptr;
+}
+
+bool MaterialLoader::ParseMaterialData(const Containers::Array<Core::uint8>& data, Material* material) {
+    return true;
+}
+
+} // namespace Resources
+} // namespace XCEngine