feat: add native road compiler provider

blender/osmassets/catalog.py

@@ -48,6 +48,14 @@ ROAD_LAYERS = [
 
 SCENE_STYLE_FILE = "osm2streets_scene_style.json"
 
+# Native-road output intentionally maps into existing scene material layers.
+# It is a provider adapter, not a second scene-layer registry.
+NATIVE_ROAD_LAYERS = (
+    {"source": "road_surface", "material_layer": "road_surface"},
+    {"source": "intersection_surface", "material_layer": "intersection_surface"},
+    {"source": "sidewalk_surface", "material_layer": "sidewalks"},
+)
+
 
 # Material specs.  `kind` selects the builder:
 #   solid      — flat base colour