Creates a fully settled sale with minimal input — the server looks up prices, taxes and auto-applied fees, assigns the next invoice number on the location's cloud register, and records a single payment for the bill total. Requires the p/c-bill permission on the location. This is the simplest way for an app to record a sale. Note: lines[].unit is required in practice (omitting it errors) even though it is declared nullable — pass the variant's unit, e.g. "pcs".