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/Shader/Shader.cpp

@@ -0,0 +1,40 @@
+#include "Resources/Shader.h"
+
+namespace XCEngine {
+namespace Resources {
+
+Shader::Shader() = default;
+
+Shader::~Shader() = default;
+
+void Shader::Release() {
+    m_sourceCode.Clear();
+    m_compiledBinary.Clear();
+    m_uniforms.Clear();
+    m_attributes.Clear();
+    m_rhiResource = nullptr;
+    m_isValid = false;
+}
+
+void Shader::SetSourceCode(const Containers::String& source) {
+    m_sourceCode = source;
+}
+
+void Shader::SetCompiledBinary(const Containers::Array<Core::uint8>& binary) {
+    m_compiledBinary = binary;
+}
+
+void Shader::AddUniform(const ShaderUniform& uniform) {
+    m_uniforms.PushBack(uniform);
+}
+
+void Shader::AddAttribute(const ShaderAttribute& attribute) {
+    m_attributes.PushBack(attribute);
+}
+
+void Shader::SetRHIResource(class IRHIShader* resource) {
+    m_rhiResource = resource;
+}
+
+} // namespace Resources
+} // namespace XCEngine