添加cadfs_to_cdsl代码，优化cad生成

onshape_to_cdsl/src/onshape_to_cdsl/download.py

@@ -129,6 +129,8 @@ def download_one(ref: PartStudioRef, authorization: str, raw_root: Path, *, time
         ("tessellated_edges", part_studio_path(ref, "/tessellatededges"), "tessellated_edges.json", common),
         ("shaded_views", part_studio_path(ref, "/shadedviews"), "shaded_views.json", {"viewMatrix": "front", "outputWidth": 512, "outputHeight": 512, "edges": "show", "showAllParts": "true"}),
     ]
+    if os.environ.get("ONSHAPE_FAST_STEP") == "1":
+        resources = [item for item in resources if item[0] not in {"tessellated_faces", "tessellated_edges", "shaded_views"}]
     # These document and Part Studio evidence endpoints are independent.  A
     # bounded fan-out keeps an interactive acquisition from being cut off
     # before it can reach the asynchronous STEP export, while preserving the
@@ -136,12 +138,13 @@ def download_one(ref: PartStudioRef, authorization: str, raw_root: Path, *, time
     worker_count = max(1, min(16, int(os.environ.get("ONSHAPE_DOWNLOAD_WORKERS", "4"))))
     with ThreadPoolExecutor(max_workers=worker_count, thread_name_prefix="onshape-download") as executor:
         artifacts.extend(executor.map(lambda item: _save(client, root, *item), resources))
-    artifacts.extend(_sketch_artifacts(client, root))
     artifacts.extend([
         _save(client, root, "parasolid", part_studio_path(ref, "/parasolid"), "model.x_t", {"version": "0", "includeExportIds": "true", "binaryExport": "false"}, "text/plain, application/octet-stream"),
         _save(client, root, "gltf", part_studio_path(ref, "/gltf"), "model.gltf", {**common, "outputSeparateFaceNodes": "true"}, "model/gltf+json, application/octet-stream"),
         _export_step(client, root, ref.sample_id, poll_seconds, poll_limit),
     ])
+    if os.environ.get("ONSHAPE_FAST_STEP") != "1":
+        artifacts.extend(_sketch_artifacts(client, root))
     manifest = {"schema": "onshape_to_cdsl.raw_sample.v1", "source": ref.as_dict(), "resource_count": len(artifacts), "downloaded_count": sum(item.status in {"downloaded", "reused"} for item in artifacts), "unavailable_count": sum(item.status not in {"downloaded", "reused"} for item in artifacts), "resources": [asdict(item) for item in artifacts]}
     write_json(root / "manifest.json", manifest)
     return manifest