macOS setup: missing scripts/env/select_venv.py and toast notification crash on Python 3.13

[cerocca]

Environment:

• macOS (iMac)
• Python 3.13

Issues found:

1. setup-unix.sh fails because apps/desktop/scripts/env/select_venv.py does not exist.
   Workaround: manually create venv with python3.13 -m venv .venv.nix

2. Toast notifications crash with TclError on macOS + Python 3.13:
   TclError: expected boolean value but got "after#945"
   in toast_notification.py line 146: self.toast_window.overrideredirect(True)

Steps to reproduce:

1. Clone repo on macOS
2. Run ./setup-unix.sh
3. Setup fails at virtual environment step
4. After manual venv creation, app launches but toast notifications crash

Note: Despite the toast error, the app works and device is recognized correctly.

[tomhollingworth]

I'm getting this same error when running