Replace pause-on-idle with full server shutdown after IDLE_SHUTDOWN_SECONDS
(default 5 minutes). Next visitor gets a fresh simulation instance.
- Idle checker stops server and clears st.cache_resource
- init_session_state detects stopped server and recreates fresh state
- Clears instruments and history for clean restart
Configurable via IDLE_SHUTDOWN_SECONDS environment variable.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>