Change project structure;

Added new c# binding;

native/header/Algorithm/GGXMultiScatter.h

@@ -0,0 +1,17 @@
+#ifndef GGX_MULTI_SCATTER_H
+#define GGX_MULTI_SCATTER_H
+
+#include "Common.h"
+#include "cglm/struct/vec3.h"
+
+// Initialize the tiny LUT. Safe to call multiple times.
+void ggx_ms_init_lut_once(void);
+
+// Heitz-style multiple-scattering GGX approximation (Smith model).
+// Returns a broad lobe (Lambertian-shaped in shading space).
+vec3s ggx_multi_scatter_lambert(vec3s f0, float NoV, float NoL, float roughness);
+
+// Expose E(NoV, roughness) for lobe mixing / pdfs.
+float ggx_ms_E(float NoV, float roughness);
+
+#endif // GGX_MULTI_SCATTER_H