Read a channel’s calendar and set it against the bookings held

Fetches the connection’s iCal export, or reads a feed sent as ical, and reconciles it against this unit. A stay the feed shows and we have no record of is written held rather than sold: a calendar carries dates and rarely money, so it blocks the nights and earns nothing until somebody prices it. Where the feed’s descriptions state a payout, a model is asked once per template where it sits, the answer is proved against those descriptions, and each stay is then priced from its own description only while it still reads as that template. A stay we already hold has the channel’s reference filled in. Nothing is cancelled and no overlap is resolved here; both raise a task instead.