feat: add public seller directory

packages/contracts/package.json

@@ -10,6 +10,7 @@
     "./product": "./product.js",
     "./public-listing": "./public-listing.js",
     "./public-inventory": "./public-inventory.js",
-    "./public-product": "./public-product.js"
+    "./public-product": "./public-product.js",
+    "./public-seller": "./public-seller.js"
   }
 }

packages/contracts/public-seller.js

@@ -0,0 +1,12 @@
+function toIsoString(value) {
+  return value instanceof Date ? value.toISOString() : value;
+}
+
+export function toPublicSellerDto(seller) {
+  return {
+    id: seller.id,
+    displayName: seller.displayName,
+    createdAt: toIsoString(seller.createdAt),
+    updatedAt: toIsoString(seller.updatedAt),
+  };
+}