Scale service at start and end of day

[chriswilty]

I've noticed that AWS costs are about $3.50 per day when the fargate service and load balancer are up and running.

We can reduce these costs by bringing the service down at end of day, then up again at start of next, plus only having the service available mon-fri. At this stage it's unclear how that will affect availability of the load balancer, so we might need to bring that up/down as well, unless Fargate manages that for us.

In the UI, we might need to show some sort of "webapp is offline" page when the service is down, instead of showing the full app with a "could not reach service" message in the chat panel. Need to investigate this, but in any case it might be better as a separate issue.