Investigate and document strategies to debug cloud gateway outages or potential misconfiguration of Command Centre

**Describe the bug**
This initially came from me noticing that my CI pipeline [had failed to run](https://github.com/anomaly/gallagher/actions/runs/9851431972). I have been making a fair bit of changes to my command centre configuration (pending documentation) to get my 7000 demo controller working over a WAN.

This lead me to believe that I had misconfigured the Command Centre for it to stop responding to the connections from the Cloud gateway.

Upon running the tests locally I found that all of our tests were failing and hence investigated to find that there were connection timeouts. These are likely caused by:

- Misconfiguration of the Command Centre
- Outage of the Cloud gateway

This ticket is to mainly document strategies to `debug` what may be a configuration issue and what otherwise might be an outage.

We also found that there were some unexpected behaviours with CardholderDetail no longer validating. This could well be due to a pyndatic update, which should be checked out.

```
E pydantic_core._pydantic_core.ValidationError: 1 validation error for CardholderDetail
E cards.0.invitation.href
```

**To Reproduce**
Steps to reproduce the behavior:
1. run `task test`
2 Expect to see Connection failures

**Expected behavior**
All tests run and pass

**Screenshots**
NA

**Additional context**
NA