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/services/lookup.service.ts

@@ -0,0 +1,114 @@
+import { eq, and } from 'drizzle-orm'
+import type { PostgresJsDatabase } from 'drizzle-orm/postgres-js'
+import {
+  inventoryUnitStatuses,
+  itemConditions,
+  SYSTEM_UNIT_STATUSES,
+  SYSTEM_ITEM_CONDITIONS,
+} from '../db/schema/lookups.js'
+import type { LookupCreateInput, LookupUpdateInput } from '@forte/shared/schemas'
+
+function createLookupService(
+  table: typeof inventoryUnitStatuses | typeof itemConditions,
+  systemSeeds: ReadonlyArray<{ slug: string; name: string; description: string; sortOrder: number }>,
+) {
+  return {
+    async seedForCompany(db: PostgresJsDatabase, companyId: string) {
+      const existing = await db
+        .select()
+        .from(table)
+        .where(and(eq(table.companyId, companyId), eq(table.isSystem, true)))
+        .limit(1)
+
+      if (existing.length > 0) return // already seeded
+
+      await db.insert(table).values(
+        systemSeeds.map((seed) => ({
+          companyId,
+          ...seed,
+          isSystem: true,
+        })),
+      )
+    },
+
+    async list(db: PostgresJsDatabase, companyId: string) {
+      return db
+        .select()
+        .from(table)
+        .where(and(eq(table.companyId, companyId), eq(table.isActive, true)))
+        .orderBy(table.sortOrder)
+    },
+
+    async getBySlug(db: PostgresJsDatabase, companyId: string, slug: string) {
+      const [row] = await db
+        .select()
+        .from(table)
+        .where(and(eq(table.companyId, companyId), eq(table.slug, slug)))
+        .limit(1)
+      return row ?? null
+    },
+
+    async create(db: PostgresJsDatabase, companyId: string, input: LookupCreateInput) {
+      const [row] = await db
+        .insert(table)
+        .values({
+          companyId,
+          name: input.name,
+          slug: input.slug,
+          description: input.description,
+          sortOrder: input.sortOrder,
+          isSystem: false,
+        })
+        .returning()
+      return row
+    },
+
+    async update(db: PostgresJsDatabase, companyId: string, id: string, input: LookupUpdateInput) {
+      // Prevent modifying system rows' slug or system flag
+      const existing = await db
+        .select()
+        .from(table)
+        .where(and(eq(table.id, id), eq(table.companyId, companyId)))
+        .limit(1)
+
+      if (!existing[0]) return null
+      if (existing[0].isSystem && input.isActive === false) {
+        throw new Error('Cannot deactivate a system status')
+      }
+
+      const [row] = await db
+        .update(table)
+        .set(input)
+        .where(and(eq(table.id, id), eq(table.companyId, companyId)))
+        .returning()
+      return row ?? null
+    },
+
+    async delete(db: PostgresJsDatabase, companyId: string, id: string) {
+      const existing = await db
+        .select()
+        .from(table)
+        .where(and(eq(table.id, id), eq(table.companyId, companyId)))
+        .limit(1)
+
+      if (!existing[0]) return null
+      if (existing[0].isSystem) {
+        throw new Error('Cannot delete a system status')
+      }
+
+      const [row] = await db
+        .delete(table)
+        .where(and(eq(table.id, id), eq(table.companyId, companyId)))
+        .returning()
+      return row ?? null
+    },
+
+    async validateSlug(db: PostgresJsDatabase, companyId: string, slug: string): Promise<boolean> {
+      const row = await this.getBySlug(db, companyId, slug)
+      return row !== null && row.isActive
+    },
+  }
+}
+
+export const UnitStatusService = createLookupService(inventoryUnitStatuses, SYSTEM_UNIT_STATUSES)
+export const ItemConditionService = createLookupService(itemConditions, SYSTEM_ITEM_CONDITIONS)