Add recorder script edge case tests

[caryhsu]

Summary

• add recorder script generation edge-case coverage for unknown and partial events
• escape recorder-generated string values safely in script output
• cover stop_recording() behavior with mixed and incomplete event payloads

Testing

• pytest tests/test_recorder.py tests/test_client.py -q -k "ScriptGenEdgeCaseTests or stop_recording_ignores_unknown_events_in_script_output or
  stop_recording_handles_partial_event_payloads"