fix(docker): add libero_plus install workaround to generic Dockerfile.benchmark

The generic Dockerfile.benchmark was using a plain `uv pip install ".[libero_plus]"`
which silently fails to make `libero` importable due to an upstream LIBERO-plus
packaging bug. Port the dedicated clone + .pth workaround from
Dockerfile.eval-libero-plus so `docker build --build-arg BENCHMARK=libero_plus`
produces working containers.

Also fix eval worker using nonexistent `parser.parse()` — use `draccus.parse()`.

Made-with: Cursor

tests/scripts/test_eval_worker.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python
+
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from pathlib import Path
+
+from lerobot.scripts import lerobot_eval_worker
+
+
+def test_worker_main_writes_results(monkeypatch, tmp_path: Path):
+    cfg = lerobot_eval_worker.EvalWorkerConfig(
+        env="pusht",  # type: ignore[arg-type]
+        instance_id=3,
+        output_path=tmp_path / "worker.json",
+    )
+
+    monkeypatch.setattr(lerobot_eval_worker, "run_worker", lambda _cfg: {"per_task": []})
+
+    lerobot_eval_worker.worker_main(cfg)
+
+    assert cfg.output_path.exists()
+    assert cfg.output_path.read_text().strip() == '{\n  "per_task": []\n}'