feat(simulation): load combined rover collision

tests/test_simulation_projects.py

@@ -225,7 +225,7 @@ def test_service_materializes_world_manifest_and_deletes_both_copies(tmp_path: P
     assert provider.deleted == ["gsp-20260826000000-deadbeef"]
 
 
-def test_world_manifest_prefers_seed_connected_rover_terrain() -> None:
+def test_world_manifest_prefers_combined_rover_collision_world() -> None:
     manifest = _world_manifest(
         "sim-" + "a" * 32,
         [
@@ -237,12 +237,16 @@ def test_world_manifest_prefers_seed_connected_rover_terrain() -> None:
                 "role": "rover-terrain-mesh",
                 "logical_path": "rover/terrain.collision.glb",
             },
+            {
+                "role": "rover-collision-mesh",
+                "logical_path": "rover/scene.collision.glb",
+            },
         ],
     )
 
     assert manifest["collision"]["available"] is True
     assert manifest["collision"]["mesh_url"].endswith(
-        "/artifacts/rover/terrain.collision.glb"
+        "/artifacts/rover/scene.collision.glb"
     )