feat: complete inventory image and sales workflows

Commit the working vertical slices for inventory image processing and the Sale workflow, including Sale history, audited voiding, multi-item persistence, admin UI, migrations, documentation, and tests.

packages/validation/package.json

@@ -7,6 +7,7 @@
     "./inventory": "./inventory.js",
     "./image": "./image.js",
     "./listing": "./listing.js",
+    "./sale": "./sale.js",
     "./product": "./product.js"
   },
   "dependencies": {

packages/validation/sale.js

@@ -0,0 +1,45 @@
+import { z } from 'zod';
+
+const isoDate = /^\d{4}-\d{2}-\d{2}$/;
+const currencyCode = /^[A-Za-z]{3}$/;
+const saleItemSchema = z.object({
+  inventoryItemId: z.uuid(),
+  soldPriceMinor: z.int().positive(),
+  costBasisMinor: z.int().nonnegative(),
+});
+
+export const createSaleSchema = z.object({
+  inventoryItemId: z.uuid(),
+  costBasisMinor: z.int().nonnegative(),
+  saleDate: z.string().trim().regex(isoDate),
+  saleLocation: z.string().trim().max(255).optional(),
+  soldPriceMinor: z.int().positive(),
+  currency: z.string().trim().regex(currencyCode).optional(),
+  platformFeesMinor: z.int().nonnegative().optional(),
+  paymentProcessingFeesMinor: z.int().nonnegative().optional(),
+  shippingCostMinor: z.int().nonnegative().optional(),
+  taxesMinor: z.int().nonnegative().optional(),
+  otherFeesMinor: z.int().nonnegative().optional(),
+  buyerName: z.string().trim().max(255).optional(),
+  buyerContact: z.string().trim().max(255).optional(),
+  notes: z.string().trim().max(10000).optional(),
+}).strict();
+
+export const createMultiItemSaleSchema = z.object({
+  items: z.array(saleItemSchema).min(2),
+  saleDate: z.string().trim().regex(isoDate),
+  saleLocation: z.string().trim().max(255).optional(),
+  currency: z.string().trim().regex(currencyCode).optional(),
+  platformFeesMinor: z.int().nonnegative().optional(),
+  paymentProcessingFeesMinor: z.int().nonnegative().optional(),
+  shippingCostMinor: z.int().nonnegative().optional(),
+  taxesMinor: z.int().nonnegative().optional(),
+  otherFeesMinor: z.int().nonnegative().optional(),
+  buyerName: z.string().trim().max(255).optional(),
+  buyerContact: z.string().trim().max(255).optional(),
+  notes: z.string().trim().max(10000).optional(),
+}).strict();
+
+export const voidSaleSchema = z.object({
+  reason: z.string().trim().min(3).max(1000),
+}).strict();