POST /products/{productId}/variants

curl --request POST \
  --url https://admin.fanfare.io/api/products/{productId}/variants \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "inventoryQuantity": 123,
  "price": "<string>",
  "productId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "sku": "<string>"
}
'

{
  "archived": true,
  "createdAt": "2023-11-07T05:31:56Z",
  "createdBy": "<string>",
  "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "inventoryQuantity": 123,
  "organizationId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "price": "<string>",
  "productId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "sku": "<string>",
  "metadata": {},
  "primaryExternalId": "<string>",
  "primaryLastSyncedAt": "2023-11-07T05:31:56Z",
  "primarySourceVendor": "<string>",
  "primarySyncSourceId": "<string>",
  "updatedAt": "2023-11-07T05:31:56Z",
  "updatedBy": "<string>"
}