static ORIG: OnceLock<termios>Expand description
The terminal settings as they were before Term::enter.
A static rather than a field because the panic hook has to reach them, and
the hook outlives any borrow we could hand it. panic = "abort" in the
release profile does not skip hooks — it skips unwinding — so this is
still the last thing that runs before a crash, and without it a panic leaves
the shell in raw mode with no echo and no cursor.