test(shops): add entity-schema cross-check for sellable loot bags

The migration spec only asserted SQL substrings against a mocked
QueryRunner and had no getMetadataArgsStorage() check that ShopOffer's
column options and partial unique indexes actually match the new
schema. Since ts-jest does not type-check in this package
(isolatedModules: true), this is the only automated guard against
entity/migration drift -- matches the house convention in
npc-system.migration.spec.ts and loot-bags.migration.spec.ts.

apps/api/src/database/migrations/sellable-loot-bags.migration.spec.ts

@@ -1,6 +1,7 @@
 import 'reflect-metadata';
-import { QueryRunner } from 'typeorm';
+import { getMetadataArgsStorage, QueryRunner } from 'typeorm';
 import { SellableLootBags1796000000000 } from './1796000000000-SellableLootBags';
+import { ShopOffer } from '../../shops/entities/shop-offer.entity';
 
 async function runUp(): Promise<string[]> {
   const query = jest.fn().mockResolvedValue(undefined);
@@ -73,3 +74,47 @@ describe('SellableLootBags1796000000000', () => {
     );
   });
 });
+
+describe('slice 0.8.5 entity schema', () => {
+  function column(target: unknown, propertyName: string) {
+    return getMetadataArgsStorage().columns.find(
+      (candidate) =>
+        candidate.target === target && candidate.propertyName === propertyName,
+    );
+  }
+
+  it('lets the item target sit empty when the offer sells a bag instead', () => {
+    expect(column(ShopOffer, 'itemDefinitionId')?.options.nullable).toBe(true);
+  });
+
+  it('gives a bag offer its own nullable uuid target', () => {
+    const lootBagDefinitionId = column(ShopOffer, 'lootBagDefinitionId');
+    expect(lootBagDefinitionId?.options.type).toBe('uuid');
+    expect(lootBagDefinitionId?.options.nullable).toBe(true);
+  });
+
+  it('requires every offer to carry its bypass conditions, empty or not', () => {
+    const bypassConditions = column(ShopOffer, 'bypassConditions');
+    expect(bypassConditions?.options.type).toBe('jsonb');
+    expect(bypassConditions?.options.nullable).toBeFalsy();
+  });
+
+  it('declares both partial unique indexes with their WHERE clauses', () => {
+    const indices = getMetadataArgsStorage().indices.filter(
+      (candidate) => candidate.target === ShopOffer,
+    );
+
+    const itemIndex = indices.find(
+      (candidate) => candidate.name === 'IDX_shop_offers_shop_item',
+    );
+    const bagIndex = indices.find(
+      (candidate) => candidate.name === 'IDX_shop_offers_shop_bag',
+    );
+
+    expect(itemIndex?.unique).toBe(true);
+    expect(itemIndex?.where).toBe('"item_definition_id" IS NOT NULL');
+
+    expect(bagIndex?.unique).toBe(true);
+    expect(bagIndex?.where).toBe('"loot_bag_definition_id" IS NOT NULL');
+  });
+});