- Add graceful shutdown with SIGTERM/SIGINT handling\n- Make model list configurable via config.yaml\n- Remove sensitive data from debug logs (log sizes instead of full bodies)\n- Handle array format in system messages (both string and []interface{})\n- Update config.yaml with new models structure
- Remove unused buildToolCalls() function (logic is inlined)\n- Simplify randomString() using global rand (Go 1.20+)\n- Use dynamic timestamps instead of hardcoded 1234567890\n- Add time import to converter.go