feat(ugc): glitter flecks (LEGO-AnimUV) and milky satin in made models

Glitter colors (Materials.xml type glitter, glitter_colors 114,117) go into
S21_Glitter_Model and, transparent, S21_GlitterAlpha_Model (shader_glitter,
default 21, LEGO-AnimUV). Their shapes get box-projected UVs, an
NiTexturingProperty with a stored 128 px mipmapped fleck texture
(NiSourceTexture + NiPersistentSrcTextureRendererData, as the client's own
env_ag_ocean-maelstrom.nif) and two NiTextureTransformControllers looping
the base map's translation (glitter_size, glitter_density, glitter_speed).
The shader lays the texture over the vertex color by its alpha and outputs
the vertex alpha, so transparent glitter blends as S01_Alpha does.

Satin colors (satin_colors, LEGO's opal colors) stay in S01_Alpha but get
satin_opacity and are whitened by satin_whiten.

NifFile reads the base map's scroll speed (uvScroll) from the controllers;
the icon draws still flecks, the UGC 3D view and the LXFML viewers moving
ones. stats.json counts the glitter groups. With shader_glitter 0 and no
satin colors the files are the same bytes as before (tested). Also keeps
glow_emissive for the icon (it was reset by the icon settings).

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

dUgcServer/CMakeLists.txt

@@ -2,6 +2,7 @@
 set(DUGC_SOURCES
 	"UgcBricks.cpp"
 	"UgcFormats.cpp"
+	"UgcGlitter.cpp"
 	"UgcIconParams.cpp"
 	"UgcIconPose.cpp"
 	"UgcJobs.cpp"
@@ -40,5 +41,5 @@ target_link_libraries(UgcServer ${COMMON_LIBRARIES} dWeb dServer dUgc)
 
 # Rendering is far too slow unoptimized (minutes a model instead of seconds), so it is optimized in every build type
 if(NOT MSVC)
-	set_source_files_properties("UgcRender.cpp" "UgcModel.cpp" "UgcPalette.cpp" PROPERTIES COMPILE_OPTIONS "-O2")
+	set_source_files_properties("UgcRender.cpp" "UgcModel.cpp" "UgcPalette.cpp" "UgcGlitter.cpp" PROPERTIES COMPILE_OPTIONS "-O2")
 endif()