Add opt() preprocessor that coerces empty strings to undefined before Zod
validation. Applied to every optional string field in account, member,
identifier, supplier, product, inventory unit, tax exemption, payment
method, and lookup schemas. Fixes forms rejecting blank optional fields.
Replace unit_status and item_condition pgEnums with company-scoped lookup
tables that support custom values. Add account_payment_method table,
tax_exemption table with approve/revoke workflow, and CRUD routes for
processor links. Validate inventory unit status/condition against lookup
tables at service layer.
- category table with hierarchical parent_id, sort ordering, soft-delete
- supplier table with contact info, account number, payment terms
- CRUD routes for both with search on suppliers
- Zod validation schemas in @forte/shared
- Products will link to suppliers via join table (many-to-many)
- 26 tests passing
