Mobile displays a different author than Desktop for workflow messages

## Summary

- Mobile displays relay-signed workflow messages under the relay pubkey instead of the attributed workflow owner.
- This creates a second, ghost-looking identity even though the workflow owner already exists in the channel.
- Observed in below screenshot where `PostHog Alerts` owns the workflow but `2e69236f…` authors its messages.

## Reproduction

1. Create a workflow owned by a named profile.
2. Have the workflow send a channel message through the relay.
3. Open the channel in Mobile.
4. Observe the relay pubkey where the workflow owner's name and avatar should appear.

## Expected behavior

Workflow messages should display the same author in Mobile as they do in Desktop.