fully specify ln addr url

pages/api/lnurlp/[username]/index.js

@@ -7,7 +7,7 @@ export default async ({ query: { username } }, res) => {
   }
 
   return res.status(200).json({
-    callback: `/api/lnurlp/${username}/pay`, // The URL from LN SERVICE which will accept the pay request parameters
+    callback: `https://stacker.news/api/lnurlp/${username}/pay`, // The URL from LN SERVICE which will accept the pay request parameters
     minSendable: 1000, // Min amount LN SERVICE is willing to receive, can not be less than 1 or more than `maxSendable`
     metadata: [[
       'text/plain', // must always be present