The physics engine runs continuously, so pausing charts was misleading - users might think the simulation stopped when it didn't. Charts now always update automatically. Also fix Streamlit deprecation warnings by replacing use_container_width with width parameter (will be removed after 2025-12-31). 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>