feat: implement 4 export extensions with engines, API routes, and workspaces
- EU Sales List: engine, CSV/XML generators, Skatteverket format, tests
- VAT Monitor: moms box mapping, revenue breakdown, validation, tests
- Intrastat: product registry, SCB CSV generator, threshold tracking, tests
- Currency Receivables: FX exposure, unrealized gain/loss calc, tests
- Shared utilities: EU country list, moms box mapping
- API routes for report generation and file downloads
- Workspace UI components for all 4 extensions
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Emil
0764bc11a6