- falcode.ts: add child.on('error') handlers so a missing notify binary
(e.g. /bin/true on NixOS) can no longer take down pi via uncaughtException
- scripts/oc-notify.sh: real notifier (notify-send + ntfy) replacing the no-op
- oc-notify.sh also deployed to ~/.local/state/falcode-zellij/ on all machines
