Refresh repository indicators promptly

### The feature request

Repository list status indicators can be stale when GitHub Desktop starts or when the repository picker is opened because the background repository indicator updater only starts on a delayed periodic cadence.

This is most visible when opening the repository picker shortly after launch: repositories with local changes, ahead commits, or behind commits can still show stale indicator state until the scheduled updater runs.

### Proposed solution

Request a repository indicator refresh as soon as the initial repositories load, when the repository foldout opens, and when repository indicators are re-enabled.

The existing background fetch throttling should remain in place so remote fetches are not made more aggressive; the change should only make the local indicator refresh scheduling more responsive.

### Additional context

The linked pull request was narrowed to this prompt-refresh behavior so it can be reviewed independently from any broader configuration or repository-picker filtering changes.