Computes the mensualité, échéancier, coût total and TAEG of a French
fixed-instalment loan in Decimal arithmetic, and emits the four anonymised
sample offers as either JSON or a Rust fixtures module.
Conventions (taux mensuel proportionnel, arrondi ROUND_HALF_UP au centime,
dernière échéance ajustée pour solder le CRD) are verified against a real
amortisation table via the `verify` subcommand, and cross-checked against the
ANIL simulator on 2026-08-03.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
