Add blueprint for flux users

[canton7]

We should be able to create a fairly simple blueprint to control the inverter for flux users.

1. Force charge during the flux rate period
2. Self use during the day rate period
3. Top-up to 100% before the peak rare starts?
4. Export as much as possible during the peak rate
5. Self use until the flux rate period starts again

None of that requires much in the way of statistics or prediction, so an open-loop blueprint might work just fine.

Needs some experimentation...