continuing to flesh out some todos from the initial tests. I've added a layer between the Resource and its available Booking Intervals in the shape of Availability. This can be used to mark something as only available between a certain period or interval (e.g. 9-5 weekdays etc) or used to mark something as unavailable for a period or interval, such as maintenance windows etc.

Also in this run, I've been playing with injecting Entities. There's a lot of complexity involved but I think it's working to make things easy to unit test which is the end goal. I want to be able to quickly and cheaply add a fully-tested interval.