[Bug]: Handle expiring GitHub OAuth App Tokens

### Description

Currently, the system assumes that GitHub OAuth App Tokens cannot expire. This is only true if the user has explicitly opted out of the expiration:

### Steps to reproduce

1. Create a new GitHub OAuth App
2. Observe that token experiation is on
3. Wait for 8h - the token expires
4. Now the system forces you to redo your setup.

### Logs or screenshots

_No response_

### Environment

_No response_

Start by reproducing the setup with a GitHub OAuth App whose token expiration is enabled, then trace the GitHub OAuth token handling and the path taken after the token expires. Done means an expired token is handled without forcing the user to redo the setup; add or update coverage for that expiration path if the project has tests for OAuth handling.

Written by the indexing model from the issue text.