Backend footgun linter

A linter to automatically catch and fix footguns for you.

- [ ] Make sure you call `.SetContext(ctx)` on every call to `restyclient.R()`, to make sure all HTTP requests are tracked in telemetry.
- [ ] Make sure you call `timezone.Now()` instead of `time.Now()` to guarantee that `.Year()/.Day()/etc...` are all in the correct timezone.