v0.1.0 of hobex_hps

Dart & Flutter client for the hobex Payment Service (HPS) local REST API: card payments, refunds, pre-auth and voids on hobex / Sunmi card terminals. Changelog excerpt: - Initial hobex_hpsrelease: typed Dart client for the local hobex Payment Service (HPS) REST API. - Operations: payment, pre-auth, pre-auth capture, pre-auth cancel, refund (incl. referenced), void/cancel, abort, account verification (AVT), transaction status (v2) and terminal diagnosis. - TransactionResponseand Diagnosismodels, Cvm/ HpsTransactionTypeenums, and typed exceptions (HpsHttpException, HpsConnectionException). - Replaces the previous experimental TC-ECR binary socket prototype.