media_seen shoud be <taken_at><view_time>

[taeyeonssupdate]

media_seen shoud be <taken_at><view_time>
taken_at < view_time for post and story, story under 24 hour

[subzeroid]

Maintainer note: if Instagram's current seen payload requires a different timestamp shape, please open a focused issue or PR with sanitized current request/response details. The helper should follow the current app behavior rather than a guessed constant format.