Add sub-asset import and mesh asset support

- Implement sub-asset import for mesh/model assets with manifest generation and deterministic GUIDs
- Extend AssetCatalog for sub-asset tracking and management
- Update AssetRegistry and ImportCoordinator for sub-asset workflows
- Add mesh asset parsing, GPU upload, and resource management
- Update mesh data structures for meshlet groups/hierarchy and LODs
- Improve tests for sub-asset import and mesh handling
- Enhance mocks for mesh asset testing and resource mapping
- Fix path handling and native DLL loading issues
- Miscellaneous bug fixes and refactoring

src/ThridParty/Ghost.DXC/Api.cs

@@ -15,9 +15,9 @@ public partial class Api
         // NOTE: Currently only support Windows.
         if (libraryName == "dxcompiler")
         {
-            NativeLibrary.TryLoad("runtimes/win-x64/native/dxil.dll", out _);
+            NativeLibrary.TryLoad(Path.Combine(AppContext.BaseDirectory, "runtimes", "win-x64", "native", "dxil.dll"), out _);
 
-            if (NativeLibrary.TryLoad("runtimes/win-x64/native/dxcompiler.dll", out var dxcHandle))
+            if (NativeLibrary.TryLoad(Path.Combine(AppContext.BaseDirectory, "runtimes", "win-x64", "native", "dxcompiler.dll"), out var dxcHandle))
             {
                 return dxcHandle;
             }