all timestamp fields in database should have `_at` suffix
This is popular approach for naming timestamps:
- https://opensource.zalando.com/restful-api-guidelines/#235
- https://www.omise.co/upgrade-guide-2017-to-2019#new-naming-conventions
- https://app.sugarwod.com/developers-api-docs
In Go this is At suffix. Examples:
- in DB: stats_collected_at
- in Go: StatsCollectedAt
In Stork 'created' columns should be renamed to created_at.