Slack notifications in Signals is unconfigurably

Clicking on `Settings` -> `Signals` -> `Connect Slack workspace` routes to a series of steps on the web that seem to work as they route back to the Code app, but the no Slack workspace ever gets connected

<img width="3270" height="2042" alt="Image" src="https://github.com/user-attachments/assets/91d176fd-2c65-4374-bc86-443daf91b530" />