Add lookup tables, payment methods, tax exemptions, and processor link APIs

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.

packages/backend/src/db/schema/inventory.ts

@@ -8,7 +8,6 @@ import {
   integer,
   numeric,
   date,
-  pgEnum,
 } from 'drizzle-orm/pg-core'
 import { companies, locations } from './stores.js'
 
@@ -44,21 +43,9 @@ export const suppliers = pgTable('supplier', {
   updatedAt: timestamp('updated_at', { withTimezone: true }).notNull().defaultNow(),
 })
 
-export const conditionEnum = pgEnum('item_condition', [
-  'new',
-  'excellent',
-  'good',
-  'fair',
-  'poor',
-])
-
-export const unitStatusEnum = pgEnum('unit_status', [
-  'available',
-  'sold',
-  'rented',
-  'in_repair',
-  'retired',
-])
+// NOTE: item_condition and unit_status pgEnums replaced by lookup tables.
+// See lookups.ts for inventory_unit_status and item_condition tables.
+// Columns below use varchar referencing the lookup slug.
 
 export const products = pgTable('product', {
   id: uuid('id').primaryKey().defaultRandom(),
@@ -97,8 +84,8 @@ export const inventoryUnits = pgTable('inventory_unit', {
     .references(() => companies.id),
   locationId: uuid('location_id').references(() => locations.id),
   serialNumber: varchar('serial_number', { length: 255 }),
-  condition: conditionEnum('condition').notNull().default('new'),
-  status: unitStatusEnum('status').notNull().default('available'),
+  condition: varchar('condition', { length: 100 }).notNull().default('new'),
+  status: varchar('status', { length: 100 }).notNull().default('available'),
   purchaseDate: date('purchase_date'),
   purchaseCost: numeric('purchase_cost', { precision: 10, scale: 2 }),
   notes: text('notes'),