refactor(runtime): remove dataset replay mode

tests/runtime/test_cli.py

@@ -1,6 +1,7 @@
 from types import SimpleNamespace
 from unittest.mock import MagicMock
 
+import pytest
 import torch
 
 from lerobot.runtime.cli import _build_rollout_runtime_io, _parse_args
@@ -19,6 +20,11 @@ def test_parse_args_preserves_rollout_robot_overrides():
     assert "--robot.calibration_dir=/tmp/calibration" in args.raw_argv
 
 
+def test_parse_args_rejects_removed_dataset_replay_flags():
+    with pytest.raises(SystemExit):
+        _parse_args(["--policy.path=checkpoint", "--dataset.repo_id=dataset"])
+
+
 def test_rollout_runtime_io_uses_context_processors():
     robot = MagicMock()
     robot.robot_type = "mock_robot"