2f83f232c6
Add test coverage for invoices, transactions, bookkeeping, and supplier invoice API routes. Includes test helpers (createMockRequest, parseJsonResponse, createMockRouteParams, createQueuedMockSupabase) and fixture factories (makeInvoice, makeCustomer, makeSupplier, makeSupplierInvoice, makeCompanySettings). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>