Charger fallback policy does not activate immediately

[Flix6x]

It looks like the fallback schedule only starts at the next PTU, causing a delay of up to 15 minutes (or 1 hour, if that is the event_resolution of the market). This may be caused by the function data.models.planning.utils.get_prices, in which case this issue wouldn't be limited to just fallback policies: any schedule would start with an instruction to stand idle until the next PTU.

Possible fix: widen the query_window passed to get_prices by the market's event_resolution, on both sides.