Better timestamps

[pjhul]

Original issue: https://github.com/PostHog/squeak-react/issues/50

Before we get to a 525,600 minutes sort of situation, it might make sense to cap these "X days ago" at a month, then start to use X months ago or something that scales a little better.

[pjhul]

Recommendation via @ajsharp:

https://day.js.org/docs/en/plugin/relative-time