Use dynamic api base path for preview images

client/src/components/RoomTile.svelte

 <script>
-    import { roomsToDetachFrom, randomQueryString } from '../stores.js';
+    import { roomsToDetachFrom, randomQueryString, API_BASE_URL } from '../stores.js';
 
     export let uid;
-    $: previewSrc = "http://localhost:3000/api/preview/" + uid + $randomQueryString;
+    $: previewSrc = API_BASE_URL + "/preview/" + uid + $randomQueryString;
     export let url;
     export let name = '???';
     export let userCount = -1;

client/src/stores.js

@@ -5,6 +5,7 @@ const POLL_FOR_UPDATES = true;
 const POLL_INTERVAL = 2500;
 const REFRESH_QUERY_STRING_INTERVAL = 5000;
 
+
 export const rooms = readable([], function start(set) {
   let fetchLock = false;
   const fetchRooms = async () => {