fix medialinks sans ls0 (closes #809);

on a browser's very first visit, the first page load would not hydrate
correctly, initializing msel without file-IDs, causing medialinks
(#gf-0f6f5c0d) to throw an error

copyparty/web/up2k.js

@@ -3427,7 +3427,8 @@ if (QS('#op_up2k.act'))
     goto_up2k();
 
 apply_perms({ "perms": perms, "frand": frand, "u2ts": u2ts });
-fileman.render();
+if (ls0)
+    fileman.render();
 
 
 (function () {