Track voucher_type_at_purchase on gift card creation. Apply VAT at gift card purchase (SPV), at redemption (MPV). Use transaction-aware GetCardByIDQuerier for till saved card lookups. Apply VAT to all booking payments (split records, terminal, tip, checkout). Add TotalVATAmount and TotalNetAmount to PaymentSummary responses.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>