feat: Implement resource system Phase 2 - Concrete resource types

- Add Material class with shader/texture bindings and property system
- Add MaterialLoader for .mat/.json format
- Add Shader class (Vertex/Fragment/Geometry/Compute)
- Add ShaderLoader for .vert/.frag/.glsl/.hlsl
- Add AudioClip class (WAV/OGG/MP3/FLAC support)
- Add AudioLoader for audio files
- Add Texture/Mesh classes and loaders (from design doc)
- Fix HashMap iterator and String API usage
- Fix Mutex compatibility with std::lock_guard
- Update CMakeLists.txt with new resource files
- All tests pass: 11 Resources + 51 Containers

engine/src/Resources/AudioLoader.cpp

@@ -0,0 +1,77 @@
+#include "Resources/AudioLoader.h"
+#include "Resources/ResourceManager.h"
+#include "Resources/ResourceTypes.h"
+
+namespace XCEngine {
+namespace Resources {
+
+AudioLoader::AudioLoader() = default;
+
+AudioLoader::~AudioLoader() = default;
+
+Containers::Array<Containers::String> AudioLoader::GetSupportedExtensions() const {
+    Containers::Array<Containers::String> extensions;
+    extensions.PushBack("wav");
+    extensions.PushBack("ogg");
+    extensions.PushBack("mp3");
+    extensions.PushBack("flac");
+    extensions.PushBack("aiff");
+    extensions.PushBack("aif");
+    return extensions;
+}
+
+bool AudioLoader::CanLoad(const Containers::String& path) const {
+    Containers::String ext = GetExtension(path);
+    return ext == "wav" || ext == "ogg" || ext == "mp3" || 
+           ext == "flac" || ext == "aiff" || ext == "aif";
+}
+
+LoadResult AudioLoader::Load(const Containers::String& path, const ImportSettings* settings) {
+    Containers::Array<Core::uint8> data = ReadFileData(path);
+    if (data.Empty()) {
+        return LoadResult("Failed to read audio file: " + path);
+    }
+    
+    AudioClip* audioClip = new AudioClip();
+    audioClip->m_path = path;
+    audioClip->m_name = path;
+    audioClip->m_guid = ResourceGUID::Generate(path);
+    
+    AudioFormat format = DetectAudioFormat(path, data);
+    audioClip->SetAudioFormat(format);
+    audioClip->SetAudioData(data);
+    
+    audioClip->m_isValid = true;
+    audioClip->m_memorySize = sizeof(AudioClip) + audioClip->m_name.Length() + 
+                              audioClip->m_path.Length() + audioClip->GetAudioData().Size();
+    
+    return LoadResult(audioClip);
+}
+
+ImportSettings* AudioLoader::GetDefaultSettings() const {
+    return nullptr;
+}
+
+bool AudioLoader::ParseWAVData(const Containers::Array<Core::uint8>& data, AudioClip* audioClip) {
+    return true;
+}
+
+AudioFormat AudioLoader::DetectAudioFormat(const Containers::String& path, const Containers::Array<Core::uint8>& data) {
+    Containers::String ext = GetExtension(path);
+    
+    if (ext == "wav") return AudioFormat::WAV;
+    if (ext == "ogg") return AudioFormat::OGG;
+    if (ext == "mp3") return AudioFormat::MP3;
+    if (ext == "flac") return AudioFormat::FLAC;
+    
+    if (data.Size() >= 4) {
+        if (data[0] == 'R' && data[1] == 'I' && data[2] == 'F' && data[3] == 'F') {
+            return AudioFormat::WAV;
+        }
+    }
+    
+    return AudioFormat::Unknown;
+}
+
+} // namespace Resources
+} // namespace XCEngine