feat: use last_read_at timestamp when available

[setchy]

Prefer last_read_at time when available. Helpful in conditions where you open a notification, then mark is as unread. Most noticeable when a decent amount of time has lapsed between reading and unreading.

Before

After

[setchy]

Hard to tell if this is a regression in the GitHub API around how they are setting updated_at timestamps when updating read/done notifications to unread... Feels unusual that I'm only just noticing this today... 🤷

Our GraphQL searches to return Discussions appear now finding no results for these types of notifications (as shown in the screenshots above) since it's using a time window of updatedAt timestamp - 2hrs. I've raised #1104 since I think we can remove the timestamp-range filtering from the query...

[afonsojramos]

I see, so switching between unread/read would update the notification, that makes sense!