Fix: Add headless config to AppLauncher in export_env_for_envhub

[yjmade]

Fixes #29

Problem

In export_env_for_envhub, AppLauncher is initialized without the headless parameter, causing cfg.headless to be implicitly overwritten by AppLauncher defaults. This results in errors when running on headless servers:

RuntimeError: Cannot render 'rgb_array' when the simulation render mode is 'NO_GUI_OR_RENDERING'

Solution

1. Add headless: True and enable_cameras: False to default config in _parse_config
2. Pass headless=cfg.headless to AppLauncher initialization

Changes

• lw_benchhub/utils/envhub_utils.py: Updated export_env_for_envhub function

Testing

On a headless server, running export_env_for_envhub should no longer raise RuntimeError.