Lack of network connectivity during recovery key setup leads to confusing error

### Steps to reproduce

1. Go to "Settings -> Encryption"
2. Lose network connectivity (e.g. put phone into airplane mode)
3. Tap "Get recovery key"
4. Tap "Generate your recovery key"

### Outcome

#### What did you expect?

A useful error

#### What happened instead?

A spinner:

After 30 seconds, an unhelpful error:

### Your phone model

_No response_

### Operating system version

_No response_

### Application version and app store

EX 26.08.4

### Homeserver

_No response_

### Will you send logs?

No

### Will you submit a Pull Request?

No

Start by reproducing the recovery-key flow from Settings → Encryption while the phone is in airplane mode. Trace the recovery-key setup path and its network-failure handling; done means the flow stops promptly and shows a useful error instead of an indefinite spinner followed by an unhelpful message.

Written by the indexing model from the issue text.