Refactor asset pipeline to use file paths, improve import

- Switched asset handler interfaces and implementations to use file paths instead of FileStreams for all operations.
- Refactored mesh asset structure and parsing, moved meshlet logic to MeshProcessor, and introduced hierarchical MeshNode types.
- Updated texture asset handling: switched to bits-per-channel, improved mipmap/cubemap generation, and SPMD HDRI support.
- Updated shader asset handlers to use file paths and split code compilation logic.
- Improved asset registry: added event debouncing, better path handling, and import time/hash tracking.
- Added source generator for IAssetSettings registration to support polymorphic JSON serialization.
- Updated dependencies and tests; various minor fixes and cleanups.

src/Test/Ghost.MicroTest/Program.cs

@@ -1,4 +1,4 @@
 using Ghost.MicroTest;
 using Ghost.Test.Core;
 
-TestRunner.Run<StbIBindingTest>();
+TestRunner.Run<NvttBindingTest>();