Adds CSV export alongside the Excel snapshot export: two buttons on the Export hub
write the bet journal and the paper-trading ledger to UTF-8 (BOM) .csv files in the
configured export directory and toast the path — mirroring the Excel use case's
write-and-return-path contract. CSV needs no third-party library, so it lives in the
Application layer behind a pure RFC-4180 formatter.
- Csv formatter (RFC 4180 escaping) + ExportToCsvUseCase (journal + ledger, batched
title join, returns null when there's nothing to export); registered; Export hub
buttons + en/ru resx.
- 11 tests: formatter escaping/Document + use-case empty-state + real-file write to a temp dir.
