8dd1200e

By: Tom Sydney Kerckhove <syd@cs-syd.eu>

Define each VAT rate exactly once

The standard rate was written down four times: as 0.081 in vatRateRatio, as 8.1
in the Stripe importer's setting default, as "8.1 %" in the Typst formatter, and
as "8.1" in the E-MWST declaration, where a TODO already asked for this.

The literal is now the only definition, in the form the law and the declaration
state it in, and the ratio and the number are derived from it exactly and
without failing.  The Typst string and the declaration's literal come out
byte-identical, which the unchanged golden output is the evidence for.

Timeline