sepa 0.3.0

SEPA payment utilities: IBAN validation (ISO 13616 + country registry), BIC validation (ISO 9362), pain.001 SCT + SCT Inst XML builder (pain.001.003.03 / pain.001.001.09), pain.008 SDD CORE + B2B XML builder (pain.008.003.02), pain.002 status report parser, camt.053 statement parser, camt.054 notification types. Zero I/O. No async. No f64 in monetary arithmetic.