feat: surface seller contact methods on public detail pages

apps/api/tests/http/public-listing-routes.test.js

@@ -36,6 +36,9 @@ function createTestApp() {
           conditionId: 'condition-1',
           askingPriceMinor: 2499,
           status: 'PENDING',
+          sellerDisplayName: 'Pika Collectibles',
+          sellerContactEmail: 'hello@pika.example',
+          sellerContactPhone: null,
         };
       },
     },
@@ -72,6 +75,8 @@ test('returns a public listing detail or a not-found response', async (testConte
 
   assert.equal(detailResponse.statusCode, 200);
   assert.equal('inventoryItemId' in detailResponse.json().data, false);
+  assert.equal(detailResponse.json().data.sellerDisplayName, 'Pika Collectibles');
+  assert.equal(detailResponse.json().data.sellerContactEmail, 'hello@pika.example');
   assert.equal(missingResponse.statusCode, 404);
   assert.equal(missingResponse.json().error.code, 'LISTING_NOT_FOUND');
 });

apps/api/tests/http/public-product-routes.test.js

@@ -21,6 +21,9 @@ function createTestApp() {
           name: 'Pikachu Plush',
           slug,
           description: 'A friendly plush.',
+          sellerDisplayName: 'Pika Collectibles',
+          sellerContactEmail: 'hello@pika.example',
+          sellerContactPhone: null,
           createdAt: new Date('2026-09-07T00:00:00.000Z'),
           updatedAt: new Date('2026-09-07T00:00:00.000Z'),
         };
@@ -51,6 +54,9 @@ test('returns a public product without private seller identity', async (testCont
     eventName: null,
     releaseYear: null,
     tags: [],
+    sellerDisplayName: 'Pika Collectibles',
+    sellerContactEmail: 'hello@pika.example',
+    sellerContactPhone: null,
     createdAt: '2026-09-07T00:00:00.000Z',
     updatedAt: '2026-09-07T00:00:00.000Z',
   });