- MQTT import_cost_total / export_revenue_total now anchor fixed-fee / tax-credit
accrual at max(contract start, first recorded period), so standing charges for
untracked pre-recording days are no longer folded into the running total.
- Add energy.import_cost_today / energy.export_revenue_today (monetary,
total_increasing) that reset at server-local midnight, for per-day cost
aggregation in Home Assistant alongside the running totals.
- ContractForm add-version mode prefills the contract's open version values, so
only the fields that actually change need editing.