Request from API doesn't update User#last_seen_at

[david (David Taylor)]

@david

we have the DISCOURSE_VISIBLE header for XHR requests, we could certainly make that work on API requests as well.

You can now set DISCOURSE_VISIBLE=“true” on API requests, and Discourse will update the last_seen time for the user

https://github.com/discourse/discourse/commit/af86cf46dc003f19ba52f71826f057884f1119ba