BUG: Reposts Should Provide ReasonRepost

Right now, Contrails cannot find the repost URI to include in a `SkeletonItem.reason`:

```typescript
type ReasonRepost = {
  $type: 'app.bsky.feed.defs#skeletonReasonRepost'
  repost: string // repost URI
}
```

I think this means there's no "reposted by X" in the app.

This is due to the fact that getAuthorFeed doesn't supply the repost URI.