feat(tests): Add test_mesh tool for OBJ loading and normal visualization

Implemented a new standalone test tool 'test_mesh' to:
- Load a .obj file specified via command line.
- Display the mesh with rotation and basic lighting on a tiled floor.
- Provide a '--debug' option to visualize vertex normals as cyan lines.
- Updated asset_packer to auto-generate smooth normals for OBJs if missing.
- Fixed various WGPU API usage inconsistencies and build issues on macOS.
- Exposed Renderer3D::GetVisualDebug() for test access.
- Added custom Vec3 struct and math utilities for OBJ parsing.
This tool helps verify mesh ingestion and normal computation independently of the main demo logic.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/3d/visual_debug.h b/src/3d/visual_debug.h
index 6173fc4..ebccf45 100644
--- a/src/3d/visual_debug.h
+++ b/src/3d/visual_debug.h
@@ -8,6 +8,7 @@
 
 #include "gpu/gpu.h"
 #include "util/mini_math.h"
+#include "3d/object.h"
 #include <vector>
 
 struct DebugLine {
@@ -27,6 +28,8 @@ class VisualDebug {
 
   void add_aabb(const vec3& min, const vec3& max, const vec3& color);
 
+  void add_mesh_normals(const mat4& transform, uint32_t num_vertices, const MeshVertex* vertices);
+
   // Render all queued primitives and clear the queue
   void render(WGPURenderPassEncoder pass, const mat4& view_proj);