fix: refine link creation response structure

Returns link object separately from shortLink in response to maintain clearer API structure and prevent unnecessary data duplication in the response payload

server/api/link/create.post.ts

@@ -24,6 +24,6 @@ export default eventHandler(async (event) => {
     })
     setResponseStatus(event, 201)
     const shortLink = `${getRequestProtocol(event)}://${getRequestHost(event)}/${link.slug}`
-    return { ...link, shortLink }
+    return { link, shortLink }
   }
 })