Mulitpass instance on macOS is often found listed as running but uncontactable, after being left running but unused for several hours

**Describe the bug**
I am using
```
multipass 1.16.1+mac
multipassd 1.16.1+mac
```
on macOS Sequoia on an M1 Mac.

On leaving the Mac slept for some hours, and then returning, it is quite frequently the case that one of the multipass instances says that it is running, but cannot be contacted (`shell`). Attempting to `stop` or `restart` it hangs, and it then enters 'unknown state'.

This can be fixed by restarting the multipass service:
```
$ sudo launchctl unload /Library/LaunchDaemons/com.canonical.multipassd.plist
$ sudo launchctl load /Library/LaunchDaemons/com.canonical.multipassd.plist
```

The issue may, or may not, depend on the Mac sleeping - I have not tested leaving for a similar length of time with sleep disabled.

**To Reproduce**
I am unclear how to reproduce except - use the multipass instance for a bit. Go away leaving it running. Come back after a few hours. It is often (but not always) in the listed running but uncontactable state.

**Expected behavior**
Instances left running are still running and usable when I come back.

**Logs**
Here is the log file:

[multipassd.log.zip](https://github.com/user-attachments/files/23831883/multipassd.log.zip)

There is a restart at `2025-11-29T05:14:57.463`, I was trying to access the instance but failing immediately before this, but there appear to be no related log lines.

**Additional info**
- OS: macOS 26.2
- CPU architecture or model: Apple M1
- `multipass version`
```
multipass 1.16.1+mac
multipassd 1.16.1+mac
```
- `multipass info clang-test`
```
$ multipass info clang-test
Name: clang-test
State: Running
Snapshots: 1
IPv4: 192.168.2.18
Release: Ubuntu 24.04.3 LTS
Image hash: 499fa6088985 (Ubuntu 24.04 LTS)
CPU(s): 1
Load: 0.00 0.00 0.00
Disk usage: 10.7GiB out of 48.4GiB
Memory usage: 239.4MiB out of 952.6MiB
Mounts: --
```
- `multipass get local.driver`
```
qemu
```

**Additional context**
I am not sure that it is relevant, but I have been using fuse+sshfs to mount drives out of my multipass instances (e.g. I want to compile files in multipass = much faster; but I want to view and edit in an IDE in macOS = has a GUI). However to try to rule it out as in issue, I have been unmounting my fuse mounts at the end of a development session, before leaving the multipass instance unattended (!) - and it has not stopped the issue.