[az][gui] Responsivity issues in the UI when enabling/disabling zones

**Describe the bug**
In the UI, when using the "Change zone availability" feature, if clicking randomly on the button multiple times, the toggle will either not move, or the UI will lock temporarily (waiting for daemon), or a grey widget will appear.

**To Reproduce**
https://github.com/user-attachments/assets/49d67fa5-74bb-402a-9feb-f16c778e417f

**Expected behavior**
Ideally, while the action is the toggles should enter a disabled state while the action is being executed, with a notif indicating that it's in progress.
No broken widget should appear at any time.

**Logs**
Please provide logs from the daemon, see [Access logs](https://canonical.com/multipass/docs/stable/how-to-guides/troubleshoot/access-logs/) on where to find them on your platform.

**Additional info**
- OS: Win 11 Pro
- CPU architecture or model: x64
- `multipass version`
multipass 1.17.0-dev.ci6331+ga58dcf2e.win
multipassd 1.17.0-dev.ci6331+ga58dcf2e.win

**Additional context**
Add any other context about the problem here.

Start by reproducing the issue in the desktop UI using the “Change zone availability” feature on Windows 11, repeatedly clicking the toggle while observing the daemon wait and grey widget behavior. Trace the UI action and its daemon interaction; done means repeated clicks leave toggles safely disabled during execution, show progress notification, and never produce a broken widget.

Written by the indexing model from the issue text.