- VendorService: CRUD with unique name validation per tenant
- ExpenseService: create, approve, post, void with full JE integration
- Auto-generated EXP-NNNN expense numbers per tenant
- JE posting: DR category expense account, CR cash (1010) or bank (1020)
- Optional approval workflow: requireApproval flag controls DRAFT-only vs immediate post
- Void reverses JE via JournalEntryService.reverseEntry
- Custom category creation with COA account validation
- System categories protected from deletion
- API routes: expenses CRUD, approve, categories CRUD, vendors CRUD
- Migration: add_expense_vendor_models applied via db push + resolve
- 15 integration tests covering all expense lifecycle scenarios
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>