Port scripts/infer_payments.py parse_czk_amount to Go as
internal/domain/money.ParseCZK. Preserves the Czech-locale heuristic
(comma = decimal sep; 2+ dots = thousand seps; single dot = decimal)
and returns (float64, error) so callers can opt into Python's
silent-zero contract via v, _ := money.ParseCZK(s).
All expected values verified against live Python on 2026-05-06.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
