feat: add acquisition API foundation

Add acquisition persistence, cost-basis calculation, seller-scoped admin routes, contracts, validation, migration, and focused application/HTTP tests.

apps/api/tests/application/acquisition-service.test.js

@@ -0,0 +1,41 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+
+import { createAcquisitionService } from '../../src/modules/acquisitions/services/acquisition-service.js';
+
+test('creates an owned acquisition and calculates cost basis', async () => {
+  let received;
+  const service = createAcquisitionService({
+    acquisitionRepository: {
+      async createForSeller(input) {
+        received = input;
+        return { status: 'CREATED', acquisition: { id: 'acquisition-1', ...input.acquisition } };
+      },
+    },
+  });
+
+  const result = await service.create({
+    sellerId: 'seller-1',
+    inventoryItemId: 'inventory-1',
+    method: 'PURCHASE',
+    costMinor: 1000,
+    shippingMinor: 150,
+    taxMinor: 75,
+    otherFeesMinor: 50,
+    estimatedTradeValueMinor: 200,
+  });
+
+  assert.equal(received.sellerId, 'seller-1');
+  assert.equal(result.costBasisMinor, 1075);
+});
+
+test('rejects acquisition for an inventory item outside the seller account', async () => {
+  const service = createAcquisitionService({
+    acquisitionRepository: { async createForSeller() { return { status: 'NOT_FOUND' }; } },
+  });
+
+  await assert.rejects(
+    () => service.create({ sellerId: 'seller-1', inventoryItemId: 'inventory-1', method: 'PURCHASE', costMinor: 100 }),
+    (error) => error.code === 'INVENTORY_NOT_FOUND' && error.statusCode === 404,
+  );
+});