V6.9.0

Added

• Optional inputs for the backup circuit: a half-hourly energy meter of the load on the
  inverter's UPS output and a helper in which the blueprint learns its 48-slot profile
  (watt-hours per half hour). Both are recorded per half hour; nothing is controlled yet.
  The profile is the basis for a backup reserve in a later version.

Changed

• The discharge floor is planned per half hour over a rolling 72-hour window instead of per
  calendar day. The forecast trust applies by lead time (under 24 hours in full, then the two
  configured factors) to each slot's surplus, deficits count in full, and the running sum is
  clamped at zero: deficits before a sunny stretch are carried by the floor itself and do not
  reduce the refill. Nothing switches at midnight or at sunrise any more; the two trust
  inputs now read "24 to 48 hours" and "48 to 72 hours ahead".
• The refill is measured up to the largest intermediate maximum, so the target is reached
  at the end of the best sun day rather than at midnight after the evening consumption.
• Tomorrow, day 3 and day 4 use their own Solcast half-hour arrays when the sensors carry
  detailedForecast; otherwise the day total is spread in today's shape. Days are matched by
  the date of their array, so a late sensor roll-over at midnight no longer shifts the horizon.
• The recording carries the half-hour arrays of the three following days (state, P10 and
  start only) and the first counted slot of the plan.
• README names the inverter setting "Battery Operation Mode: Voltage" as a reason for a
  floor that is not honoured: in that mode the SOC fields of the time-of-use programs are
  ignored.