Process trees (pty sessions, tool exec) were being SIGKILL'd immediately
without any grace period for cleanup. This prevented child processes from:
- Flushing buffers and closing files cleanly
- Closing network connections
- Terminating their own child processes
- Removing temporary files
Changes:
- Send SIGTERM to process group first (Unix)
- Wait configurable grace period (default 3s)
- Then SIGKILL if process still alive
- Windows: taskkill without /F first, then with /F after grace period
- Use unref() on timeout to not block event loop exit
Fixes#18619
Co-authored-by: James <james@openclaw.ai>
20957efa46