feat(ugc): one shape per transparent brick, as LU Toolbox leaves them

LU Toolbox's Combine Transparent is off by default, so each transparent brick
is its own object and shape (the client can sort them). combine_transparent=1
joins them as before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

dUgcServer/UgcJobs.h

@@ -24,6 +24,7 @@ namespace UgcJobs {
 		std::vector<uint32_t> lods{ 0, 2 };    // brickprimitives levels made (LU Toolbox imports LOD 0 and 2; the client has no 3)
 		UgcModel::LodDistances lodDistances;
 		std::string shaderOpaque{ "01" };      // S<shader>_Opaque_...; transparent shapes are always S01
+		bool combineTransparent{ false };      // one shape for all transparent bricks, else one per brick (Combine Transparent)
 		UgcRender::OptimizeOptions optimize;   // hidden surface removal
 		UgcRender::AoOptions ao;               // Bake Lighting (AO Only)
 		UgcRender::IconOptions icon;