2479d87afc
Slice 2 + 1b: - Bill editor: VAT-rate field → VatRateSelect dropdown (mirrors the quote editor); snapshots vatCode on create + carries it from a source quote. - getQuoteById + the invoice serializer now return vat_code, so re-editing a saved document preserves the snapshot instead of falling back to the rate→code map. Payload types (quotes + bills) carry vatCode. 72 tests pass; build green.